Screening tests
Testing for M. tuberculosis may begin with a TB screening test. This is not used as a general screen but is targeted at those who are at a high risk for contracting the disease and at those who work or live with high-risk people. The TB screening test may also be done as part of a physical examination prior to starting school or a new job.
The TB skin test is performed on the patient's skin by injecting a purified protein derivative (PPD) solution just under the skin. This provokes a hypersensitivity skin reaction (a red raised bump) in those who may have been infected by M. tuberculosis. The reaction is evaluated by a health care worker at 48 or 72 hours. Positive results may indicate a latent TB infection and should be followed by other tests, such as chest X-rays, to look for signs of active disease. False-positive results may be seen in people who have had a BCG (Bacille Calmette-Guérin) vaccination while false-negative results may be seen in those with weakened immune systems. This method of screening also requires a second visit for the results to be evaluated.
The interferon gamma release assays (IGRAs) are relatively new blood tests that can be used as an alternative or follow up to the TB skin test to help diagnose a latent TB infection. It is not affected by previous IGRA, TB skin tests, or by BCG vaccination. It does not require the patient to return in 48 to 72 hours for evaluation, and there is no local skin reaction. However, these tests have special handling and transport time restrictions. There are limited data on its use with children and those with suppressed immune systems. A positive IGRA must be followed up in a similar fashion to a positive TB skin test in order to determine if an active infection is present.
Active Tuberculosis
AFB Smear and Culture
To diagnose TB of the respiratory tract, 3 to 5 sputum specimens are collected first thing in the morning on different days when they are most likely to contain the most mycobacteria. If extrapulmonary TB is suspected, samples are collected based upon where in the body the infection is likely to be. Multiple samples of gastric (stomach) washings/aspirates or urine may be collected and submitted to the laboratory. Sometimes cerebrospinal fluid (CSF), biopsied tissue, or other body fluids are also collected.
A presumptive diagnosis of TB can be made by examining a smear of the patient's specimen under the microscope after it has been treated with a special stain to detect acid fast bacteria (AFB). Positive AFB smears are likely to indicate a TB infection since M. tuberculosis is the most common acid-fast bacillus in the lungs, but the smears cannot distinguish between the different species of "acid-fast" bacilli. A culture is required for a definitive diagnosis.
AFB cultures are performed on respiratory samples or other body fluid samples. Specialized nutrient media and prolonged incubation provide a supportive environment for the slow-growing mycobacteria. The results of cultures are definitive, but they take time - days to several weeks for positive samples. Cultures are held for six to eight weeks before being reported as negative. Once M. tuberculosis has been identified and treatment has begun, AFB smears and cultures are used to monitor the effectiveness of treatment.
TB molecular tests (nucleic acid amplification test, NAAT) detect the genetic material of M. tuberculosis. They are useful because they can generally provide results in about 24 hours as opposed to the several weeks required for culture. The 2009 guidelines from the Center for Disease Control and Prevention (CDC) recommend that a TB NAAT be performed on at least one sample from someone with signs and symptoms of TB. The results are evaluated in conjunction with results of an AFB smear. Like AFB smears, both positive and negative results must be confirmed with AFB cultures. However, if both AFB smear and molecular test are positive, the doctor will begin treatment of the affected person before results of the culture are available.
Susceptibility testing is done to determine if the strain causing the infection has developed resistance to the drugs used most often to treat the infection. Testing can be performed on media containing the antibiotic used to treat TB, which can take several weeks for the result, or testing can be done in a broth culture and results can be available in 7 days. There are molecular tests available that can also be used to detect specific genes in the DNA of the bacteria that confer resistance to certain drugs. However, these tests are currently only available in areas outside of the United States.
A liquid culture method called Microscopic-Observation Drug-Susceptibility (MODS) assay has been developed. This method takes only about 7 days to diagnose TB and detects bacterial resistance to antibiotics. It can recognize the presence of mycobacteria much more quickly than traditional culture and can help health care providers diagnose and treat the disease at an earlier stage. It has the potential to help control the spread of infectious TB in resource-limited countries. The benefits and limitations of this test are being evaluated.
A rapid, automated molecular test that detects the genetic material of TB has been developed to help diagnose infections. Within two hours, the test can detect the presence of TB and determine if it is resistant to one of the most commonly prescribed drugs used to treat the infection, rifampin. In 2010, the World Health Organization endorsed use of the test, but it is not currently sold in the US as it has not yet been approved by the US Food and Drug Administration (FDA).
Non-Laboratory Tests
X-rays are often used as a follow-up to positive TB skin tests to look for signs of mycobacteria growth and to help determine whether someone has active tuberculosis or a latent TB infection. Infection with TB can cause a number of characteristic findings on x-rays, including cavities (holes) and calcification in organs such as the lungs and kidneys. More information on radiological tests can be found at RadiologyInfo.
http://labtestsonline.org/understanding/conditions/tuberculosis/?start=3
Showing posts with label diagnosis tuberculosis. Show all posts
Showing posts with label diagnosis tuberculosis. Show all posts
Monday, 18 July 2011
Tuesday, 3 May 2011
TUBERCULOSIS: British screening misses most incoming latent TB
27 April 2011 by Jessica Hamzelou
London may owe its reputation as the tuberculosis capital of Europe to the UK's TB screening programme. A new study suggests the current policy for screening immigrants from countries with a known TB problem misses 71 per cent of those who carry the disease but do not display symptoms. A policy change that would cost little more could bring that number down to 8 per cent.
British policy is to X-ray people arriving from countries known to have 40 or more cases of active TB for every 100,000 people. However, X-rays are effective at identifying active infections only: individuals who don't display symptoms of disease remain undetected. "Their X-ray scans are normal," says Ajit Lalvani at Imperial College London.
Latent TB can take anywhere from a few weeks to a lifetime to develop into an active form of the disease, but around 5 per cent of carriers will develop full-blown TB within a few years, says Lalvani.
Immigrants arriving in the UK from countries with 500 or more cases of active TB per 100,000 people face a more stringent test that will detect latent TB. It involves exposing a blood sample to TB antigens. If a person's immune system has been exposed to such an antigen before, the blood's T-cells will respond by releasing a protein known as interferon gamma; otherwise, the T-cells will do nothing. People with both active and latent forms of the disease can be identified in this way.
Lalvani and his colleagues studied three busy TB screening centres in London, Leeds and Blackburn – regions with high levels of TB in the immigrant population – between 2008 and 2010. Their analysis suggested that the current rules for TB screening were missing 71 per cent of cases of latent TB, which may prove costly to treat if they develop into an active form of the disease.
£3000 per case
To find a cost-effective alternative, the group analysed the estimated costs and benefits associated with lowering the latent TB screening threshold in order to screen more immigrants. They found that by using latent-TB screening for people from countries with TB rates above 150 per 100,000 – rather than 500 per 100,000 – they would be able to catch 92 per cent of latent TB cases.
The overall cost of extending latent screening would be around £20,000 per case of TB averted – "around £3000 more per case averted than the current [screening] programme", says Lalvani. He suggests that extending latent screening this way would actually save money, because it may cost a lot more to deal with cases of full-blown TB arising from latent infections: as well as treating the patient, everyone that they have been in contact with must be screened to make sure they have not become infected, which may be expensive.
However, the group has not yet carried out a full cost analysis to confirm that extra screening is cheaper in the long run.
Journal reference: The Lancet, DOI: 10.1016/s1473-3099(11)70069-x
http://www.newscientist.com/article/dn20424-british-screening-misses-most-incoming-latent-tb.html
London may owe its reputation as the tuberculosis capital of Europe to the UK's TB screening programme. A new study suggests the current policy for screening immigrants from countries with a known TB problem misses 71 per cent of those who carry the disease but do not display symptoms. A policy change that would cost little more could bring that number down to 8 per cent.
British policy is to X-ray people arriving from countries known to have 40 or more cases of active TB for every 100,000 people. However, X-rays are effective at identifying active infections only: individuals who don't display symptoms of disease remain undetected. "Their X-ray scans are normal," says Ajit Lalvani at Imperial College London.
Latent TB can take anywhere from a few weeks to a lifetime to develop into an active form of the disease, but around 5 per cent of carriers will develop full-blown TB within a few years, says Lalvani.
Immigrants arriving in the UK from countries with 500 or more cases of active TB per 100,000 people face a more stringent test that will detect latent TB. It involves exposing a blood sample to TB antigens. If a person's immune system has been exposed to such an antigen before, the blood's T-cells will respond by releasing a protein known as interferon gamma; otherwise, the T-cells will do nothing. People with both active and latent forms of the disease can be identified in this way.
Lalvani and his colleagues studied three busy TB screening centres in London, Leeds and Blackburn – regions with high levels of TB in the immigrant population – between 2008 and 2010. Their analysis suggested that the current rules for TB screening were missing 71 per cent of cases of latent TB, which may prove costly to treat if they develop into an active form of the disease.
£3000 per case
To find a cost-effective alternative, the group analysed the estimated costs and benefits associated with lowering the latent TB screening threshold in order to screen more immigrants. They found that by using latent-TB screening for people from countries with TB rates above 150 per 100,000 – rather than 500 per 100,000 – they would be able to catch 92 per cent of latent TB cases.
The overall cost of extending latent screening would be around £20,000 per case of TB averted – "around £3000 more per case averted than the current [screening] programme", says Lalvani. He suggests that extending latent screening this way would actually save money, because it may cost a lot more to deal with cases of full-blown TB arising from latent infections: as well as treating the patient, everyone that they have been in contact with must be screened to make sure they have not become infected, which may be expensive.
However, the group has not yet carried out a full cost analysis to confirm that extra screening is cheaper in the long run.
Journal reference: The Lancet, DOI: 10.1016/s1473-3099(11)70069-x
http://www.newscientist.com/article/dn20424-british-screening-misses-most-incoming-latent-tb.html
Sunday, 24 April 2011
New Test Effective for Detection of Tuberculosis
April 19, 2011.
Test for Mycobacterium tuberculosis, rifampicin resistance shows high sensitivity and specificity
Diagnosis of Mycobacterium tuberculosis (MTB) and rifampicin resistance (RIF), detected by the MTB/RIF test, is accurate and feasible in resource-poor countries, according to a study published online April 19 in The Lancet.
Diagnosis of Mycobacterium tuberculosis (MTB) and rifampicin resistance (RIF), detected by the MTB/RIF test, is accurate and feasible in resource-poor countries, according to a study published online April 19 in The Lancet.
Catharina C. Boehme, M.D., from the Foundation for Innovative New Diagnostics in Geneva, Switzerland, and colleagues evaluated whether the Xpert MTB/RIF test was feasible, robust, and accurate. Between 2009 and 2010, sputum smears and cultures of 6,648 tuberculosis patients were collected, and one-off direct MTB-RIF testing was compared to other detection methods. Indicators of robustness included indeterminate rate and between-site performance. The time to detection, reporting, treatment, and patient dropouts were compared between different tuberculosis-detection techniques.
The investigators found that one-off MTB/RIF testing detected 90.3 percent of 1,033 culture-confirmed tuberculosis cases, and microscopy detected 67.1 percent of 1,041 cases. The MTB/RIF test was 76.9 percent sensitive and 99.0 percent specific for smear-negative, culture-positive patients. Test sensitivity was 94.4 percent and specificity was 98.3 percent for rifampicin resistance. In contrast to microscopy, test sensitivity did not decrease significantly in patients with HIV co-infection. Average tuberculosis detection time was zero days for MTB/RIF, one day for microscopy, and 30 and 16 days for solid and liquid cultures, respectively. Average resistance detection time was 20 and 106 days for line-probe assay and conventional drug-susceptibility test, respectively. The MTB/RIF test reduced the average treatment time from 56 to five days for smear-negative tuberculosis. The indeterminate rate was 2.4 and 4.6 percent for MTB/RIF and cultures, respectively.
"Our findings suggest that decentralized MTB/RIF test implementation is feasible and could lead to an improvement in tuberculosis care and control," the authors write.
Several study authors disclosed financial relationships with Cepheid, which developed the MTB/RIF test and partially funded the study.
http://www.doctorslounge.com/index.php/news/pb/19477
Monday, 28 March 2011
TUBERCULOSIS: need to solve problems around the pricing and supply of DR-TB medicines
As a new rapid diagnostic test, endorsed by the World Health Organisation (WHO), will finally help detect more people with drug-resistant tuberculosis (DR-TB), there was need to solve problems around the pricing and supply of DR-TB medicines, according to a report by international medical humanitarian organisation Médecins Sans Frontières (MSF).
The DR-TB is on the rise, but less than 7 per cent of 4,40,000 new cases each year receive treatment. It kills 150,000 people in the world annually, according to the WHO. India is one of the countries with the highest burden of DR-TB cases in the world, with more than 99,000 new cases each year.
The MSF report, released to mark World TB Day, shows that DR-TB drugs are riddled with persistent supply and price problems that must be urgently addressed.
The report examines medicines used to treat DR-TB according to the number of suppliers, quality assurance and price, based on information obtained from the Global Drug Facility and drug manufacturers.
The report highlights that four of the recommended DR-TB medicines are available from only one quality-assured generic source.
Relying on a sole supplier whose production could be disrupted or stopped at any time always carries a risk of dangerous treatment interruption for patients. For example, supplies of injectable drug kanamycin were disrupted in 2010, leading to a temporary global stock out.
“In India and several other countries, resistance to TB drugs is a serious public health issue, which cannot be allowed to get worse,” said Blessina Kumar of Stop TB Partnership.
“Patients have been stuck in a vicious circle – not enough people are diagnosed, and drug supply problems along with high prices stand in the way of putting more people on treatment.”
Additionally, the MSF report found that several DR-TB medicines are very expensive, with prices for two drugs having increased by more than 600 per cent and one drug by more than 800 per cent over the last decade.
A 24-month DR-TB treatment regimen can cost as much as $9,000 for one patient — 470 times more than the $19 per patient it costs to cure standard, drug-sensitive TB.
“Now that we have a new test that can detect DR-TB in less than two hours instead of three months, we're going to see many more people who will need reliable drug supplies to get treated,” said Joanna Ladomirska, Medical Coordinator for MSF in India.
“We need to see some immediate action to improve access to DR-TB drugs so that more people are started on treatment and transmission of this disease is reduced. This is particularly important in India, given the high burden of DR-TB here,” said Ladomirska.
The low demand for DR-TB drugs had made the market unattractive for producers, which was reinforcing the supply and price problems.
One way to kick start increased production of some of these drugs is for donors to guarantee purchase volumes for several years to producers upfront.
Other mechanisms such as better forecasting of the mid-to long-term needs for DR-TB drugs are also needed to help attract more producers to the market, to improve supply security and increase competition that helps brings prices down.
“With faster diagnosis and better treatment models of the DR-TB, we need to fix the supply and price issues with DR-TB drugs. We also need to see newer drugs developed,” said Ladomirska.
http://www.thehindu.com/health/article1564679.ece
The DR-TB is on the rise, but less than 7 per cent of 4,40,000 new cases each year receive treatment. It kills 150,000 people in the world annually, according to the WHO. India is one of the countries with the highest burden of DR-TB cases in the world, with more than 99,000 new cases each year.
The MSF report, released to mark World TB Day, shows that DR-TB drugs are riddled with persistent supply and price problems that must be urgently addressed.
The report examines medicines used to treat DR-TB according to the number of suppliers, quality assurance and price, based on information obtained from the Global Drug Facility and drug manufacturers.
The report highlights that four of the recommended DR-TB medicines are available from only one quality-assured generic source.
Relying on a sole supplier whose production could be disrupted or stopped at any time always carries a risk of dangerous treatment interruption for patients. For example, supplies of injectable drug kanamycin were disrupted in 2010, leading to a temporary global stock out.
“In India and several other countries, resistance to TB drugs is a serious public health issue, which cannot be allowed to get worse,” said Blessina Kumar of Stop TB Partnership.
“Patients have been stuck in a vicious circle – not enough people are diagnosed, and drug supply problems along with high prices stand in the way of putting more people on treatment.”
Additionally, the MSF report found that several DR-TB medicines are very expensive, with prices for two drugs having increased by more than 600 per cent and one drug by more than 800 per cent over the last decade.
A 24-month DR-TB treatment regimen can cost as much as $9,000 for one patient — 470 times more than the $19 per patient it costs to cure standard, drug-sensitive TB.
“Now that we have a new test that can detect DR-TB in less than two hours instead of three months, we're going to see many more people who will need reliable drug supplies to get treated,” said Joanna Ladomirska, Medical Coordinator for MSF in India.
“We need to see some immediate action to improve access to DR-TB drugs so that more people are started on treatment and transmission of this disease is reduced. This is particularly important in India, given the high burden of DR-TB here,” said Ladomirska.
The low demand for DR-TB drugs had made the market unattractive for producers, which was reinforcing the supply and price problems.
One way to kick start increased production of some of these drugs is for donors to guarantee purchase volumes for several years to producers upfront.
Other mechanisms such as better forecasting of the mid-to long-term needs for DR-TB drugs are also needed to help attract more producers to the market, to improve supply security and increase competition that helps brings prices down.
“With faster diagnosis and better treatment models of the DR-TB, we need to fix the supply and price issues with DR-TB drugs. We also need to see newer drugs developed,” said Ladomirska.
http://www.thehindu.com/health/article1564679.ece
Saturday, 26 March 2011
TUBERCULOSIS: SOUTH AFRICA: Quick and easy TB diagnosis puts pressure on treatment
Photo: Lee Middleton/IRIN: Simpler and quickerKHAYELITSHA, 24 March 2011 (PlusNews) - A promising new diagnostic test for detecting drug-resistant tuberculosis (DR-TB) quickly and reliably is finally available, said a new report by Médecins Sans Frontières (MSF).
The possibility that the number of DR-TB cases might treble in South Africa, which has a high TB-burden, highlights the use of this new tool in relation to problems like the pricing and supply of DR-TB medication.
The "GeneXpert" machine - about the size of a milk crate - provides a fully automated nucleic acid amplification test (NAAT) that is effective in the early diagnosis of TB, multidrug-resistant TB (MDR-TB), and TB patients co-infected with HIV, which is more difficult to diagnose.
"I'm so proud to finally have this test," said Xoliswa Harmans, a former patient with extensively drug-resistant TB (XDR-TB) and HIV, whose diagnosis in 2008 took six weeks. "It was very difficult [waiting for my results]. I was very sick. I couldn't eat and was losing weight," said Harmans, who now works as a TB counsellor.
Unlike the previous "gold standard" test, which used a culture technique that could take six to eight weeks, this test - endorsed by the World health Organization (WHO) in December 2010 - provides results in about two hours and has a sensitivity rate of 90 percent.
Another advantage of the new test is its simplicity - it can be used by people who are not necessarily health
workers because sputum sample "cartridges" are simply inserted into the machine for diagnosis.
The Ubuntu Clinic in Khayelitsha, about 32km from Cape Town, is so far the only South African clinic to use the test. The township has one of the highest national and global rates for HIV and TB. In 2009, antenatal HIV prevalence was 30 percent, and the case notification rate for TB was at least 1,500 per 100,000 people annually - one of the highest levels of TB infection in the world.
"Because of the rise of HIV, TB has become more prevalent," said Dr Jennifer Hughes, DR-TB co-coordinator for MSF in Khayelitsha. "People with HIV are more susceptible to dying from TB, so if we can diagnose sooner we can get them on treatment sooner."
Patients diagnosed with DR-TB are immediately eligible for ARV treatment, whereas "normal" TB patients are eligible only if their CD4 count (which measures immune system strength) falls below 350.
An integrated, decentralized approach
Cikizwa Jonas, 56, started treatment at the Lizo Nobanda Clinic seven weeks ago. "I take 20 pills a day... After taking all the medication I get nausea and want to vomit."
The City of Cape Town, MSF, and the Western Cape provincial government started this "decentralized" pilot project in 2007 in response to the spread of drug-resistant TB. The Lizo Nobanda clinic is one of 10 in Khayelitsha that form the hub of an integrated yet decentralized community-based approach to TB-care and offers in-patient care for newly diagnosed DR-TB patients.
New patients often suffer the most severe side effects, and the clinic provides a comfortable, safe environment for patients to acclimatize to the treatment without being forced into a lengthy and often isolating hospital stay.
Fast Fact
Treating a drug-resistant TB patient for 24 months can cost up to US$9,000 - 470 times more than the $19 per patient it costs to cure standard TB
Previously, the long wait for diagnosis and poor tracking of those patients weeks later, followed by an automatic six-month stay in hospital, meant that thousands of DR-TB patients remained undiagnosed, or were diagnosed but had no access to treatment while they continued spreading the disease to others.
The patient-centred approach uses local clinics and includes methods like infection control teams, who visit patients' homes to make alterations that reduce transmission.
"We can provide care at the community and primary care health level, increase case detection and increase the number of patients on DR-TB treatment, which reduces transmission in the community," said Hughes.
"The biggest challenge [to the decentralized method] has been contesting the notion that DR-TB patients needed to be in hospital," Dr Carol Cragg, a medical officer overseeing HIV in Western Cape told a press conference at which MSF reported the first results of the programme.
Among the key successes are improved case detection (up from 118 in
2006 to 231 in 2009) and initiation of treatment (over 80 percent of patients diagnosed in 2009 and 2010 started treatment). The median time from detection to treatment initiation fell from 71 days in 2007 to 33 days in 2010.
Better drugs
Despite the improvements brought by the decentralized approach, and the rapid diagnosis available with the new test, providing treatment is still one of the chief problems.
DR-TB treatment requires standard antibiotics, many of which have severe side effects ranging from constant nausea to deafness, and must be taken as complex daily regimen of numerous pills for up to two years.
Shortages and high prices hound the DR-TB drugs, and the increased case load from using the new test will almost certainly exacerbate these problems. Studies indicate that a full roll-out of the new test could result in a three-fold increase in new DR-TB cases, and a doubling of the number of HIV-associated TB cases.
"If we find the [expected] numbers we'll have to treat them, and that will be very difficult," said Dr Gilles van Cutsem, medical coordinator at MSF in South Africa. Treating one DR-TB patient for 24 months can cost up to US$9,000, which is 470 times more than the $19 per patient it costs to cure standard, drug-sensitive TB.
"Patients have been stuck in a vicious circle - not enough people are diagnosed, and drug supply problems, along with high prices, stand in the way of putting more people on treatment," said Dr Tido von Schoen-Angerer, Executive Director of MSF’s Campaign for Access to Essential Medicines.
"The low demand for DR-TB drugs has made the market unattractive for producers, which is reinforcing supply and price problems," he noted.
TB is a curable disease that kills nearly 1.3 million people each year worldwide, and is the main cause of death in people living with HIV/AIDS in Africa. Of the 9.4 million new tuberculosis cases reported globally each year, 440,000 are multidrug resistant.
http://www.plusnews.org/report.aspx?reportID=92279
Sunday, 6 March 2011
TUBERCULOSIS: New Diagnostic Tool to Identify Active Tuberculosis Quickly and Effectively
2/20/2011 Genevensis Healthcare Communications
Newswise — Tuberculosis (TB) remains one of the most pressing public health priorities for the 21st century, with over one third of the world population infected. Active TB disease is a major issue both for the patients who require specific treatment and at a population level, since these patients are contagious. Diagnosis of active TB disease (from latent asymptomatic infection) requires several clinical, radiological, histo-pathological, bacteriological and molecular parameters.
The new diagnostic tool developed by Pr. G. Pantaleo and Dr. A. Harari allows sensitive and highly specific identification of patients with active TB disease. The study, initially designed to identify parameters of the immune response correlated to protection against TB, led to the observation that functional signatures of immune responses, i.e. the cytokines involved such as TNF-α, IL-2 and IFN-γ, were indeed correlated to the different stages of tuberculosis disease.
The originality of this flow cytometry-based assay is that the read-out is focused on the immune response and not on microbiological parameters, thus explaining its reliability and quickness. “This assay and the functional signatures of TB-specific immune responses are not only relevant for discriminating between active TB disease and latent infection but may be also instrumental in monitoring the response to TB therapy”, says Prof. Pantaleo. “The flow cytometry-based assay requires specific equipment and skillful laboratory personnel. However, further technological development is already under way to make the assay widely accessible”, says Dr Harari.
This assay is currently implemented in Lausanne as a service for clinicians in Switzerland. These observations expand the current knowledge of the immune response against TB, thus contributing to improved diagnosis and to the development of effective vaccines.
The research published involved investigators in Switzerland and South Africa. The research program was supported by the Lausanne University Hospital (CHUV) and the Swiss Vaccine Research Institute.
http://www.newswise.com/articles/publication-in-nature-medicine-reveals-new-diagnostic-tool-to-identify-active-tuberculosis-quickly-and-effectively
Newswise — Tuberculosis (TB) remains one of the most pressing public health priorities for the 21st century, with over one third of the world population infected. Active TB disease is a major issue both for the patients who require specific treatment and at a population level, since these patients are contagious. Diagnosis of active TB disease (from latent asymptomatic infection) requires several clinical, radiological, histo-pathological, bacteriological and molecular parameters.
The new diagnostic tool developed by Pr. G. Pantaleo and Dr. A. Harari allows sensitive and highly specific identification of patients with active TB disease. The study, initially designed to identify parameters of the immune response correlated to protection against TB, led to the observation that functional signatures of immune responses, i.e. the cytokines involved such as TNF-α, IL-2 and IFN-γ, were indeed correlated to the different stages of tuberculosis disease.
The originality of this flow cytometry-based assay is that the read-out is focused on the immune response and not on microbiological parameters, thus explaining its reliability and quickness. “This assay and the functional signatures of TB-specific immune responses are not only relevant for discriminating between active TB disease and latent infection but may be also instrumental in monitoring the response to TB therapy”, says Prof. Pantaleo. “The flow cytometry-based assay requires specific equipment and skillful laboratory personnel. However, further technological development is already under way to make the assay widely accessible”, says Dr Harari.
This assay is currently implemented in Lausanne as a service for clinicians in Switzerland. These observations expand the current knowledge of the immune response against TB, thus contributing to improved diagnosis and to the development of effective vaccines.
The research published involved investigators in Switzerland and South Africa. The research program was supported by the Lausanne University Hospital (CHUV) and the Swiss Vaccine Research Institute.
http://www.newswise.com/articles/publication-in-nature-medicine-reveals-new-diagnostic-tool-to-identify-active-tuberculosis-quickly-and-effectively
Sunday, 6 February 2011
TUBERCULOSIS: Diagnosis with GeneXpert equipment
by Sara Holtz, DrPH, MPH on January 31, 2011
The World Health Organization (WHO) recently endorsed a new and novel rapid test for tuberculosis (TB), especially relevant in countries most affected by the disease, and is calling for widespread use of this test and its incorporation into national plans.
MSH applauds the research and development experts who developed this new TB test and the WHO for endorsing it so quickly. The test could revolutionize TB care and control by providing an accurate diagnosis in less than two hours, compared to current tests that can take up to three months to produce results.
Evidence suggests that use of this test could result in a three-fold increase in the diagnosis of patients with drug-resistant TB and a doubling in the number of HIV-associated TB cases diagnosed in areas with high rates of TB and HIV. Finally, the test is easy and safe to use and also allows for testing in non-health facility settings, including in people’s homes.
As with all new technologies, there are some challenges that need to be overcome to roll this new test out on a large scale. The negotiated price per test sounds reasonable, however similar negotiations for other diagnostic tests (HIV tests, CD4, etc.) have met with little success. While there are global negotiated prices through WHO and other agencies, there is still huge variation of cost of diagnostics in countries. Mechanisms to ensure countries access these negotiated prices have to be well thought through for this rapid test, and as recommended in the CD4 testing in developing countries, follow the medicine’s design.
Temperature is another factor. While the technology can be implemented at any TB diagnostic center/management unit (TBMU), infrastructure considerations still need to be kept in mind because the test cartridges are stable at room temperatures (max 28 degrees C). Temperatures in tropical African, Mediterranean, Middle Eastern, and some Asian regions where the technology is needed often exceed 28 degrees C in some months of the year. More data is needed to confirm stability and performance of the reagents in such settings. Primary health facilities may not have refrigerators or air conditioners to maintain the required temperatures.
Another potential obstacle is storage space for the ‘mini-lab’ cartridges, which are quite bulky and will require considerable storage space to maintain enough stock even for a few months in any proficient TB unit. Classical TBMU in most high burden countries actually do not have dedicated store rooms for supplies and mostly make use of small cupboards and lockers to store supplies. Supply management issues require close consideration to ensure frequent deliveries of this single item. Supply chains in the countries have (or are the process) to harmonize schedules for delivery of health supplies based on individual country challenges. Instituting frequent delivery schedules may pose as additional hurdle to health systems in countries.
The GeneXpert equipment requires annual calibration. Proximity to countries of the equipment maintenance support is a practical challenge that must to be addressed from the start. The cost to TB programs to maintain hundreds of these machines will ultimately be an issue of discussion, particularly after demand for the technology has been created.
Other red flags to a large scale roll out of this new test include the cost of the machine, the daily through-put, whether the lab techs will need specialized training, whether the test is subject to user error, and whether continuous electricity is required.
These operational challenges provide an opportunity for stronger collaboration among TB control implementers and specifically to MSH with such vast experience of successfully implementing programs in challenging settings. If some or all of these issues are addressed, this test may revolutionize TB testing and finally bring TB testing into the 21st century.
http://blog.msh.org/index.php/2011/01/31/msh-applauds-new-rapid-tuberculosis-test/
The World Health Organization (WHO) recently endorsed a new and novel rapid test for tuberculosis (TB), especially relevant in countries most affected by the disease, and is calling for widespread use of this test and its incorporation into national plans.
MSH applauds the research and development experts who developed this new TB test and the WHO for endorsing it so quickly. The test could revolutionize TB care and control by providing an accurate diagnosis in less than two hours, compared to current tests that can take up to three months to produce results.
Evidence suggests that use of this test could result in a three-fold increase in the diagnosis of patients with drug-resistant TB and a doubling in the number of HIV-associated TB cases diagnosed in areas with high rates of TB and HIV. Finally, the test is easy and safe to use and also allows for testing in non-health facility settings, including in people’s homes.
As with all new technologies, there are some challenges that need to be overcome to roll this new test out on a large scale. The negotiated price per test sounds reasonable, however similar negotiations for other diagnostic tests (HIV tests, CD4, etc.) have met with little success. While there are global negotiated prices through WHO and other agencies, there is still huge variation of cost of diagnostics in countries. Mechanisms to ensure countries access these negotiated prices have to be well thought through for this rapid test, and as recommended in the CD4 testing in developing countries, follow the medicine’s design.
Temperature is another factor. While the technology can be implemented at any TB diagnostic center/management unit (TBMU), infrastructure considerations still need to be kept in mind because the test cartridges are stable at room temperatures (max 28 degrees C). Temperatures in tropical African, Mediterranean, Middle Eastern, and some Asian regions where the technology is needed often exceed 28 degrees C in some months of the year. More data is needed to confirm stability and performance of the reagents in such settings. Primary health facilities may not have refrigerators or air conditioners to maintain the required temperatures.
Another potential obstacle is storage space for the ‘mini-lab’ cartridges, which are quite bulky and will require considerable storage space to maintain enough stock even for a few months in any proficient TB unit. Classical TBMU in most high burden countries actually do not have dedicated store rooms for supplies and mostly make use of small cupboards and lockers to store supplies. Supply management issues require close consideration to ensure frequent deliveries of this single item. Supply chains in the countries have (or are the process) to harmonize schedules for delivery of health supplies based on individual country challenges. Instituting frequent delivery schedules may pose as additional hurdle to health systems in countries.
The GeneXpert equipment requires annual calibration. Proximity to countries of the equipment maintenance support is a practical challenge that must to be addressed from the start. The cost to TB programs to maintain hundreds of these machines will ultimately be an issue of discussion, particularly after demand for the technology has been created.
Other red flags to a large scale roll out of this new test include the cost of the machine, the daily through-put, whether the lab techs will need specialized training, whether the test is subject to user error, and whether continuous electricity is required.
These operational challenges provide an opportunity for stronger collaboration among TB control implementers and specifically to MSH with such vast experience of successfully implementing programs in challenging settings. If some or all of these issues are addressed, this test may revolutionize TB testing and finally bring TB testing into the 21st century.
http://blog.msh.org/index.php/2011/01/31/msh-applauds-new-rapid-tuberculosis-test/
Thursday, 27 January 2011
TUBERCULOSIS: Zambia: Making TB technology more accessible
Photo: Laura Lopez Gonzalez/IRIN
LUSAKA, 26 January 2011 (PlusNews) - New technologies are helping Zambia make the most of its scarce health workers and laboratories in the fight against tuberculosis (TB), and showing that there may be more to a container than meets the eye.
The Zambia Aids-Related TB Project (ZAMBART), a local NGO that provides testing and treatment, has introduced easy-to-use digital chest x-rays and relatively cheap made-to-order laboratories to help close gaps in stepping up the fight against TB and HIV, which are common co-infections. a country where about 39,000 new cases of TB are reported annually, these innovations could help combat the high level of undiagnosed infectious TB, the recent Zambia-South Africa TB and AIDS Reduction (ZAMSTAR) study noted.
According to UNAIDS, about 14 percent of Zambians are HIV-positive, which greatly increases their vulnerability to TB. ZAMBART estimates that about 70 percent of TB patients are co-infected with HIV, making them harder to diagnose and more likely to die from TB, the leading killer of HIV-positive people worldwide.
Technology meets task shifting
The ZAMSTAR study also found that while many patients with a chronic cough - a symptom of TB - did not seek medical attention, those who did were often poorly investigated.
After routine screening for TB, clinic staff asked TB suspects for a sputum sample. In HIV/TB co-infected patients these samples were more likely to result in a false positive result, so health workers used chest X-rays to confirm test results.
Gideon Phiri, a ZAMBART research associate based at Kanyama Clinic in the Zambian capital, Lusaka, said the facility served an estimated 14,000 households.
Housed in a small container, Kanyama’s new x-ray machine is easy to secure, and a shortage of health workers has been overcome because the machine is so easy to use that local students like Timothy Manja, now in his a third year of study at the nearby Evelyn Hone College, learnt to operate it in a day and can use the experience towards his practical training requirement.
Shortages of medical personnel, such as x-ray operators and lab technicians, have also prompted ZAMBART and Zambia’s Ministry of Health to pilot the use of high school graduates to collect and analyse sputum samples at Kanyama.
The X-rays Manja takes also form part of a database being used by the machine’s manufacturers, Delft Diagnostic Imaging, to develop a system for TB detection, in which a computer would compare a patient’s chest x-ray to a database of images so as to flag possible TB cases. This would facilitate early detection, and also reduce the heavy caseload of health professionals.
Nurse Foster Chileshe said the onsite machine decreased the time patients had to wait for x-rays, and there were fewer follow-up losses.
Good things come in containers
The new TB lab at the national reference laboratory in Lusaka, housed in a slightly larger container, is making a big difference. Barry Kosloff, of the London School of Hygiene and Tropical Medicine, ZAMSTAR’s mini-lab project manager and designer of the lab, said while the concept was not new, container-based labs had never been this sophisticated.
Labs are internationally graded according to their biosafety level, or the level of precautions taken to isolate dangerous diseases like TB.
Zambia’s first container lab ranks at 3 on a scale of 1 to 4, with 4 being the level used to control highly contagious biological agents such as hemorrhagic diseases.
“In Africa there’s a great need to expand diagnostic services, [but] up until this lab was done, if you ever wanted to get a biosafety level-3 lab, you’d have to spend three times as much money - around half a million dollars,” Kosloff told IRIN/PlusNews. His container-based labs cost about US$130,000.
In some of Africa’s national reference laboratories, staff battle funding constraints, aging infrastructure and technology, and poor infection controls that leave them frustrated and make it dangerous to test TB cultures like those grown in Kosloff’s lab.
TB cultures are particularly important in diagnosing TB in HIV-positive patients, and to determine whether patients have successfully completed treatment. Additional lab capacity would speed up diagnosis and test results, and increase the number of patients referred for treatment.
Container labs are produced, in part, by a South African manufacturer, and can be on the ground about three months after being ordered.
Despite what Kosloff called “container stigma” - because governments seemed to look down on non-permanent structures - countries like Haiti, Peru and Kenya have all expressed interest.
Because each lab is built to order, Kosloff said, it could be adapted to country-specific needs, including water tanks or generators for areas with interrupted water and power supplies.
“Some people see containers as something less than a real lab - that because it’s a container it must be poor quality - but inside it’s a beautiful lab,” he said. “It’s about people getting the best lab for the least amount of money.”
http://www.plusnews.org/report.aspx?ReportID=91738
Wednesday, 26 January 2011
TUBERCULOSIS: Testing for Tuberculosis: The Roles of Tuberculin Skin Tests and Interferon Gamma Release Assays
Alessandra Regatieri, MD; Yehia Abdelwahed, MD; Maria T. Perez, MD, FCAP; Larry M. Bush, MD, FACP 01/17/2011; Laboratory Investigation. 2011;42(1):11-16. © 2011 Nature Publishing Group
Abstract
The identification of latent tuberculosis infection (LTBI) in any individual or population has proven to carry significant importance not only for that person's health, but also for the control and eventual elimination of tuberculosis (TB) in the United States. Traditionally, the tuberculin skin test (TST) has served as the standard of care for the identification of prior exposure to Mycobacterium tuberculosis (MTB).
However, the specificity of a positive test is less than optimal. It is either due to previous vaccination intended to prevent TB or infection with nontuberculous mycobacterium (NTM). Newer tests classified as interferon-gamma release assays (IGRA) possess potential advantages over the TST when used for identifying those with MTB infection. We recently diagnosed a case of pleuropulmonary infection involving an unusual NTM, Mycobacterium interjectum (M. interjectum), in an immunocompromised man diagnosed 1 year after he had been treated for LTBI based on a reactive TST. A propos this experience, we discuss the beneficial role of IGRAs and review the literature on infection with M. interjectum.
Introduction
Historically, the tuberculin skin test (TST) has been relied upon for diagnosing persons who have been sensitized by Mycobacterium tuberculosis (MTB), a condition referred to as latent tuberculosis infection (LTBI).[1] In a TST survey conducted in 2000, an estimated 4.2% of the civilian, non-institutionalized U.S. population aged >1 year had LTBI. Although this represented a 60% decline from 1972,[2] the decrease in prevalence was not uniform across all of the segments of the population. Furthermore, approximately 9.4% of the 153,555 persons diagnosed with active tuberculosis (TB) during the 10-year period between 1998 and 2007 died either before treatment began or during therapy prior to completing the anti-tuberculous regimen. Because the rates of MTB infection and active TB vary considerably, targeted testing and the selection of those persons likely to benefit from treatment for latent infection (ie, persons who are at increased risk for a poor clinical outcome if active infection ensues), have been assigned a high priority.
Utilizing an intradermal injection of a polyvalent antigenic mixture labeled purified protein derivative (PPD), TST is designed to assess in vivo delayed-type hypersensitivity (DTH) (Type IV), thereby helping to identify those individuals who have been infected with MTB. The reliability of the TST may be influenced by its technical application and the need for a second encounter 48–72 hours after test administration in order to record any observed reaction. Currently the standard method for detecting LTBI, TST has limitations in regards to sensitivity and specificity. Conditions such as advanced age, immunocompromised states, prior vaccination with Bacillus Calmette-Guerin (BCG), and previous or current infection with nontuberculous Mycobacterium species (NTM), may hinder the interpretation of TST results.[3]
Accordingly, improved diagnostic tests to aid in the management of MTB disease have been approved by the U.S. Food and Drug Administration (FDA). Collectively known as interferon-gamma (IFN-γ) release assays (IGRAs), these novel laboratory tools have the potential advantage of heightened sensitivity and specificity, less interpreter bias, and test result availability in less than 24 hours. Additionally, the more recent of the IGRAs, QuantiFERON-TB Gold and QuantiFERON-TB GOLD In-Tube (QFT-G and QFT-GIT, Cellestis Limited, Carnegie, Victoria, Australia) and T-SPOT.TB (T-SPOT, Oxford Immunotec Limited, Abingdon, United Kingdom), are indicated for use in the diagnosis of latent as well as active infection with MTB.[4,5]
Recently, we encountered a man diagnosed with a pleural space infection involving Mycobacterium interjectum (M. interjectum) who previously had been treated with 9 months of isoniazid (INH) for LTBI following the discovery of a positive TST (12 mm of induration), performed in anticipation of treatment of an underlying rheumatologic condition with a tumor necrosis factor alpha (TNF-α) inhibitor. At the time of his positive TST, he was asymptomatic and was found to have a clear chest radiograph (CXR). A repeat CXR obtained 1 year later revealed new asymptomatic unilateral pleural thickening with an associated pleural effusion, subsequently confirmed by computerized tomographic (CT) scan imaging. His history of previous asbestos exposure prompted a thoracentesis in order to rule out the possibility of an occult mesothelioma. Upon cytologic examination, the exudative fluid was void of any cells suspicious for malignancy. However, microbiologic laboratory stains revealed the presence of acid-fast bacilli (AFB) subsequently identified as M. interjectum. Based on in vitro susceptibility test results, clarithromycin and rifabutin were administered for 6 months, during which time treatment with infliximab was discontinued. At clinical follow-up, he remained asymptomatic. However, no test of cure microbiologic data was made available. A propos this case, we discuss the potential role that an IGRA may have played in his earlier management, assuming the possibility of a false-positive TST elicited by infection with this uncommon NTM. In addition, we review the medical literature pertaining to infection with M. interjectum.
http://www.medscape.com/viewarticle/734337
Abstract
The identification of latent tuberculosis infection (LTBI) in any individual or population has proven to carry significant importance not only for that person's health, but also for the control and eventual elimination of tuberculosis (TB) in the United States. Traditionally, the tuberculin skin test (TST) has served as the standard of care for the identification of prior exposure to Mycobacterium tuberculosis (MTB).
However, the specificity of a positive test is less than optimal. It is either due to previous vaccination intended to prevent TB or infection with nontuberculous mycobacterium (NTM). Newer tests classified as interferon-gamma release assays (IGRA) possess potential advantages over the TST when used for identifying those with MTB infection. We recently diagnosed a case of pleuropulmonary infection involving an unusual NTM, Mycobacterium interjectum (M. interjectum), in an immunocompromised man diagnosed 1 year after he had been treated for LTBI based on a reactive TST. A propos this experience, we discuss the beneficial role of IGRAs and review the literature on infection with M. interjectum.
Introduction
Historically, the tuberculin skin test (TST) has been relied upon for diagnosing persons who have been sensitized by Mycobacterium tuberculosis (MTB), a condition referred to as latent tuberculosis infection (LTBI).[1] In a TST survey conducted in 2000, an estimated 4.2% of the civilian, non-institutionalized U.S. population aged >1 year had LTBI. Although this represented a 60% decline from 1972,[2] the decrease in prevalence was not uniform across all of the segments of the population. Furthermore, approximately 9.4% of the 153,555 persons diagnosed with active tuberculosis (TB) during the 10-year period between 1998 and 2007 died either before treatment began or during therapy prior to completing the anti-tuberculous regimen. Because the rates of MTB infection and active TB vary considerably, targeted testing and the selection of those persons likely to benefit from treatment for latent infection (ie, persons who are at increased risk for a poor clinical outcome if active infection ensues), have been assigned a high priority.
Utilizing an intradermal injection of a polyvalent antigenic mixture labeled purified protein derivative (PPD), TST is designed to assess in vivo delayed-type hypersensitivity (DTH) (Type IV), thereby helping to identify those individuals who have been infected with MTB. The reliability of the TST may be influenced by its technical application and the need for a second encounter 48–72 hours after test administration in order to record any observed reaction. Currently the standard method for detecting LTBI, TST has limitations in regards to sensitivity and specificity. Conditions such as advanced age, immunocompromised states, prior vaccination with Bacillus Calmette-Guerin (BCG), and previous or current infection with nontuberculous Mycobacterium species (NTM), may hinder the interpretation of TST results.[3]
Accordingly, improved diagnostic tests to aid in the management of MTB disease have been approved by the U.S. Food and Drug Administration (FDA). Collectively known as interferon-gamma (IFN-γ) release assays (IGRAs), these novel laboratory tools have the potential advantage of heightened sensitivity and specificity, less interpreter bias, and test result availability in less than 24 hours. Additionally, the more recent of the IGRAs, QuantiFERON-TB Gold and QuantiFERON-TB GOLD In-Tube (QFT-G and QFT-GIT, Cellestis Limited, Carnegie, Victoria, Australia) and T-SPOT.TB (T-SPOT, Oxford Immunotec Limited, Abingdon, United Kingdom), are indicated for use in the diagnosis of latent as well as active infection with MTB.[4,5]
Recently, we encountered a man diagnosed with a pleural space infection involving Mycobacterium interjectum (M. interjectum) who previously had been treated with 9 months of isoniazid (INH) for LTBI following the discovery of a positive TST (12 mm of induration), performed in anticipation of treatment of an underlying rheumatologic condition with a tumor necrosis factor alpha (TNF-α) inhibitor. At the time of his positive TST, he was asymptomatic and was found to have a clear chest radiograph (CXR). A repeat CXR obtained 1 year later revealed new asymptomatic unilateral pleural thickening with an associated pleural effusion, subsequently confirmed by computerized tomographic (CT) scan imaging. His history of previous asbestos exposure prompted a thoracentesis in order to rule out the possibility of an occult mesothelioma. Upon cytologic examination, the exudative fluid was void of any cells suspicious for malignancy. However, microbiologic laboratory stains revealed the presence of acid-fast bacilli (AFB) subsequently identified as M. interjectum. Based on in vitro susceptibility test results, clarithromycin and rifabutin were administered for 6 months, during which time treatment with infliximab was discontinued. At clinical follow-up, he remained asymptomatic. However, no test of cure microbiologic data was made available. A propos this case, we discuss the potential role that an IGRA may have played in his earlier management, assuming the possibility of a false-positive TST elicited by infection with this uncommon NTM. In addition, we review the medical literature pertaining to infection with M. interjectum.
http://www.medscape.com/viewarticle/734337
TUBERCULOSIS: WHO to issue guidelines against serology test for Tuberculosis
January 20, 2011
Accra, Jan. 20, GNA - The World Health Organisation (WHO) would be issuing guidelines recommending against the use of serology tests for tuberculosis because they may be causing more harm than good in high burden countries.
This is the first negative recommendation to be made by the WHO, a release issued in Accra and copied to the Ghana News Agency on Thursday said.
The unusually strong warning is based on more than six years of work by Research and Training in Tropical Diseases (TDR) and its partners at the McGill University, University of California, the Institute of Tropical Medicine, New York University and the Statens Serum Institute.
TDR, a Special Programme for Research and Training in Tropical Diseases, is a global programme of scientific collaboration that helps to coordinate, support and influence global efforts to combat a portfolio of major diseases of the poor and disadvantaged.
The release said while manufacturers market their tests as filling an important niche in point-of-care tuberculosis diagnostics, the commercial serology tests, which were sold in scores of countries, were "inaccurate and useless".
Established in 1975, TDR based in Geneva, Switzerland, is executed by the WHO and sponsored by the United Nations Children's Fund (UNICEF), United Nations Development Programme (UNDP) and the World Bank.
TDR commissioned two systematic reviews on serological tests that were published in 2007 and in collaboration with the Institute of Tropical Medicine, at Antwerp, conducted a laboratory-based evaluation of 19 rapid serological tests for TB, published in 2008.
This evaluation found out that none of the assays were of sufficient quality to replace smear microscopy as a diagnostic, while many tests had false results.
The expert group, according to the release, endorsed the findings from an updated systematic review since the TDR report in 2008 and essentially concluded that the negative policy guidance should be preceded based on the fact that the performance characteristics of these tests were far below expectation.
In addition, the quality of the data was so weak and bad that it warranted a recommendation against the use of these tests.
http://www.ghananewsagency.org/s_health/r_24591/
Accra, Jan. 20, GNA - The World Health Organisation (WHO) would be issuing guidelines recommending against the use of serology tests for tuberculosis because they may be causing more harm than good in high burden countries.
This is the first negative recommendation to be made by the WHO, a release issued in Accra and copied to the Ghana News Agency on Thursday said.
The unusually strong warning is based on more than six years of work by Research and Training in Tropical Diseases (TDR) and its partners at the McGill University, University of California, the Institute of Tropical Medicine, New York University and the Statens Serum Institute.
TDR, a Special Programme for Research and Training in Tropical Diseases, is a global programme of scientific collaboration that helps to coordinate, support and influence global efforts to combat a portfolio of major diseases of the poor and disadvantaged.
The release said while manufacturers market their tests as filling an important niche in point-of-care tuberculosis diagnostics, the commercial serology tests, which were sold in scores of countries, were "inaccurate and useless".
Established in 1975, TDR based in Geneva, Switzerland, is executed by the WHO and sponsored by the United Nations Children's Fund (UNICEF), United Nations Development Programme (UNDP) and the World Bank.
TDR commissioned two systematic reviews on serological tests that were published in 2007 and in collaboration with the Institute of Tropical Medicine, at Antwerp, conducted a laboratory-based evaluation of 19 rapid serological tests for TB, published in 2008.
This evaluation found out that none of the assays were of sufficient quality to replace smear microscopy as a diagnostic, while many tests had false results.
The expert group, according to the release, endorsed the findings from an updated systematic review since the TDR report in 2008 and essentially concluded that the negative policy guidance should be preceded based on the fact that the performance characteristics of these tests were far below expectation.
In addition, the quality of the data was so weak and bad that it warranted a recommendation against the use of these tests.
http://www.ghananewsagency.org/s_health/r_24591/
Monday, 10 January 2011
TUBERCULOSIS: Detection of latent tuberculosis by the tuberculin skin test and a whole-blood interferon-gamma release assay
Detection of latent tuberculosis by the tuberculin skin test and a whole-blood interferon-gamma release assay, and the development of active tuberculosis in HIV-seropositive persons
Diagnostic Microbiology and Infectious Disease, 01/09/2011
Santin M et al. – This study evaluated the QuantiFERON–TB Gold In–Tube (QFT–GIT; Cellestis, Carnegie, Australia) test and the tuberculin skin test (TST) for the detection of latent tuberculosis infection (LTBI) in HIV–infected adults. One hundred thirty–five HIV–seropositive persons and 135 controls underwent TST and QFT–GIT. HIV–infected patients who gave a positive result on either test were offered chemoprophylaxis.
http://www.mdlinx.com/internal-medicine/newsl-article.cfm/3414048/ZZ880582144096849473028/?news_id=1604&newsdt=010911&subspec_id=1009
Diagnostic Microbiology and Infectious Disease, 01/09/2011
Santin M et al. – This study evaluated the QuantiFERON–TB Gold In–Tube (QFT–GIT; Cellestis, Carnegie, Australia) test and the tuberculin skin test (TST) for the detection of latent tuberculosis infection (LTBI) in HIV–infected adults. One hundred thirty–five HIV–seropositive persons and 135 controls underwent TST and QFT–GIT. HIV–infected patients who gave a positive result on either test were offered chemoprophylaxis.
http://www.mdlinx.com/internal-medicine/newsl-article.cfm/3414048/ZZ880582144096849473028/?news_id=1604&newsdt=010911&subspec_id=1009
Sunday, 9 January 2011
TUBERCULOSIS: WHO recommends against inaccurate tuberculosis tests
The Lancet, 8 January 2011 : Original Text Kelly Morris
Misleading serology tests for tuberculosis could be worsening the epidemic in some high-burden countries. WHO will be issuing policy advice against their use in early 2011.
Although no international guideline recommends their use, scores of commercial serology tests for tuberculosis are being sold in high-burden countries. Some are laboratory-based tests, whereas others are rapid dipstick tests, which could fill a vital niche for a point-of-care tuberculosis diagnostic test. “If they worked, the problem of a gap in the pipeline for a point-of-care assay would have been solved decades ago”, comments Madhukar Pai, co-chair of the STOP-TB Partnership's new diagnostics working group. “The pity is that they don't work. In fact, they're inaccurate and useless.”
WHO is due to release a negative policy recommendation—the first of its kind for the organisation—on current commercial tuberculosis serodiagnostics. Results of several meta-analyses have indicated poor performance of these tests, and in 2008, an assessment of 19 commercial assays by TDR—the UN special programme for research and training in tropical diseases—found that none of the assays were good enough to replace sputum microscopy or as an add-on test to rule out tuberculosis. Manufacturers continue to claim that their tests are effective and fill a diagnostic niche, especially in sputum smear-negative patient groups.Karin Weyer, WHO coordinator of TB diagnostics and laboratory strengthening, told The Lancet that “the negative policy process is a new concept in WHO”. But, she says, the process has been identical to that for positive recommendations, such as the endorsement announced on Dec 8 of a fully automated nucleic-acid amplification test (Xpert MTB/RIF, Cepheid) to improve tuberculosis diagnosis.
The available evidence on serodiagnostic kits has now been rigorously assessed, including meta-analyses when appropriate, and reviewed by an independent WHO expert group, says Weyer. “The expert group endorsed the findings from an updated systematic review since the TDR report in 2008 and essentially concluded that we should proceed with negative policy guidance based on the fact that the performance characteristics of these tests were way below what one would want and also because the quality of the data were so weak and so bad that it warranted a recommendation against the use of these tests”, she explains.
“Everyone is aware of the consequences of bad drugs and vaccines, but nobody really thinks about bad diagnostics and what impact they can have”, comments Pai. In their report, released at the end of December, the WHO Strategic and Technical Advisory Group for TB acknowledges “the adverse impact of misdiagnosis and wasted resources on patients and health services when using these tests for the diagnosis of active TB”, and recommends WHO to proceed with written guidance advising against current serodiagnostic kits. Further targeted research is strongly recommended since potential exists for research to develop accurate serologic assays, which could fill the point-of-care niche. WHO is being careful with preparation of the negative policy so as not to stifle innovation and research investment in tuberculosis diagnostics, says Weyer.
Commercial serodiagnostic kits are widely available, but the problem is probably greatest in India, where Pai estimates that serodiagnostic kits are used on at least 1·5 million people with suspected tuberculosis every year. Such testing is not done through the Revised National TB Control Programme (RNTCP) but through the unregulated private sector, which manages a substantial proportion of tuberculosis cases. Patients pay for serodiagnostic kits, and the market is estimated conservatively at over $US15 million in India alone, compared with $65 million for the entire RNTCP.
Despite country-wide DOTS coverage by the RNTCP, India continues to have more than 2 million new cases of tuberculosis every year. Ongoing transmission will not be reduced without intensified early case detection, which first relies on access to quality diagnosis. Writing in The New Yorker on Nov 15, journalist Michael Specter described how, in India, “for most patients, the choices are bleak”—overcrowded public hospitals versus unreliable tests at unregulated private laboratories or clinics.
Everyone in the private-sector chain gets a cut of patient fees—up to $10—30 per serodiagnostic kit—especially the referring doctors and private clinicians, who are often the same individual, Specter reports. Financial incentives perpetuate this system, Pai explains, since: “a private practitioner may not order sputum microscopy because you don't make much money out of a cheap test like sputum smears. The more expensive the test ordered, the more money you get back”, he explains.
The available evidence indicates that current tests lack either the necessary sensitivity or specificity or both to be an effective diagnostic test, and for many of these tests, false results far outnumber true results. Low sensitivity means increased false-negative results, which increase morbidity, mortality, and ongoing transmission of tuberculosis. Low specificity means more false-positive results; patients might then be given 6 months of potentially toxic treatment, while their underlying pathology remains uninvestigated and undiagnosed.
Atul Loke/Panos
India has more than 2 million new cases of tuberculosis every year
Many commercial tuberculosis serology kits are manufactured in China or India, but some are from western countries, such as France, the UK, Canada, and the USA. These manufacturers are selling high volumes of their test kits in countries such as India, although their tests are not licensed or used in the countries that make them.
During WHO's systematic review process, says Weyer, “we quickly discovered that manufacturers of these commercial serodiagnostics simply change the name of the test frequently and re-market and re-sell the same test under a new brand name. So, teasing out which test belonged to which brand name and updating the previous review by TDR proved to be a real challenge, as we wanted to be as solid as we could possibly be on the actual evidence.”
The key question is how much will the WHO guidance affect the sale and use of these tests in the private sector? “The ideal is that the public sector would be attractive enough and use state-of-the-art new tests, so that patients don't feel that they need to go to the private sector to get what they think may be a better diagnosis”, says Weyer.
However, given the extent of private-sector medicine, the concept of public—private mix (PPM) is being hailed in some quarters as the key to increasing efforts to tackle tuberculosis. The final report of WHO's subgroup on PPM for tuberculosis care and control advised earlier this year that countries need to scale up PPM, and involve provider groups outside national programmes to develop national strategic plans. Recommended approaches also include certification and accreditation of care providers and laboratories, and a system for mandatory notification of tuberculosis.
To achieve PPM recommendations, regulation of private-sector medicine will need to be developed and implemented in high-burden countries. What is absent from the PPM report is recognition that regulatory frameworks for diagnostic tests are also often weak or non-existent. WHO is helping countries establish regulatory systems to review the local relevance of diagnostics, and determine whether such tests should be marketed and sold, says Weyer. But, she foresees “a long-term difficult process”, as local expertise and capacity are often limited and regulatory frameworks need to be drawn up and passed through national legal systems country by country.
“Public-private partnership is the way to go”, asserts Camilla Rodrigues, a physician at the private Hinduja Hospital, in Mumbai, India, who has trialled the Xpert MTB/RIF system for diagnosis and drug-resistance testing of tuberculosis for more than 3 years. Rodrigues would like to see physician education on the unreliability of serology in endemic regions and laboratory accreditation encouraged. National governments need to provide guidelines for tuberculosis testing with “strict regulation in place for defaulters”, she says, adding that laboratories need diagnostic algorithms and strengthened capacity both for gold-standard tests, such as culture, and validated new molecular tests.
Weyer agrees, but notes that: “PPM alone will not overcome barriers presented by the lack of country regulatory frameworks for new diagnostics”. Nevertheless, market forces could play a part in developing and implementing better tuberculosis diagnostics. If Xpert MTB/RIF or other technologies are developed to become point-of-care tests, the private sector already has the infrastructure to deliver, and effective diagnostics could successfully replace inaccurate tests, says Pai.
The chief executive of a large private Indian diagnostic laboratory chain, Sanjeev Chaudhry, told The Lancet that Super Religare Laboratories strongly concurs in discouraging use of serodiagnostic kits in Indian settings. However, mere policy change might not be effective with the current magnitude of the challenge, he says, so, “instead of change in policy by private lab(s) in isolation or even as a consortium, we seriously feel that collective and dedicated efforts are required equally by the public- and private-sector service providers”.
As pathology service providers are expected to offer and satisfy the needs of the market, Chaudry continues that “we need to have an alternative cost-effective option along with appropriate awareness among clinicians and doctors”. Rodrigues notes that “the Indian diagnostic market is thriving. There is certainly potential for low-cost, accurate, and newer tests to be produced in India which will lower the cost.”
WHO guidance will be very clear, Weyer confirms, “to reflect the current commercial serodiagnostic tests but not to jeopardise future research and new antigen and biomarker discovery programmes that would guide and inform the development of point-of-care tests”.
http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2811%2960005-6/fulltext?rss=yes
Misleading serology tests for tuberculosis could be worsening the epidemic in some high-burden countries. WHO will be issuing policy advice against their use in early 2011.
Although no international guideline recommends their use, scores of commercial serology tests for tuberculosis are being sold in high-burden countries. Some are laboratory-based tests, whereas others are rapid dipstick tests, which could fill a vital niche for a point-of-care tuberculosis diagnostic test. “If they worked, the problem of a gap in the pipeline for a point-of-care assay would have been solved decades ago”, comments Madhukar Pai, co-chair of the STOP-TB Partnership's new diagnostics working group. “The pity is that they don't work. In fact, they're inaccurate and useless.”
WHO is due to release a negative policy recommendation—the first of its kind for the organisation—on current commercial tuberculosis serodiagnostics. Results of several meta-analyses have indicated poor performance of these tests, and in 2008, an assessment of 19 commercial assays by TDR—the UN special programme for research and training in tropical diseases—found that none of the assays were good enough to replace sputum microscopy or as an add-on test to rule out tuberculosis. Manufacturers continue to claim that their tests are effective and fill a diagnostic niche, especially in sputum smear-negative patient groups.Karin Weyer, WHO coordinator of TB diagnostics and laboratory strengthening, told The Lancet that “the negative policy process is a new concept in WHO”. But, she says, the process has been identical to that for positive recommendations, such as the endorsement announced on Dec 8 of a fully automated nucleic-acid amplification test (Xpert MTB/RIF, Cepheid) to improve tuberculosis diagnosis.
The available evidence on serodiagnostic kits has now been rigorously assessed, including meta-analyses when appropriate, and reviewed by an independent WHO expert group, says Weyer. “The expert group endorsed the findings from an updated systematic review since the TDR report in 2008 and essentially concluded that we should proceed with negative policy guidance based on the fact that the performance characteristics of these tests were way below what one would want and also because the quality of the data were so weak and so bad that it warranted a recommendation against the use of these tests”, she explains.
“Everyone is aware of the consequences of bad drugs and vaccines, but nobody really thinks about bad diagnostics and what impact they can have”, comments Pai. In their report, released at the end of December, the WHO Strategic and Technical Advisory Group for TB acknowledges “the adverse impact of misdiagnosis and wasted resources on patients and health services when using these tests for the diagnosis of active TB”, and recommends WHO to proceed with written guidance advising against current serodiagnostic kits. Further targeted research is strongly recommended since potential exists for research to develop accurate serologic assays, which could fill the point-of-care niche. WHO is being careful with preparation of the negative policy so as not to stifle innovation and research investment in tuberculosis diagnostics, says Weyer.
Commercial serodiagnostic kits are widely available, but the problem is probably greatest in India, where Pai estimates that serodiagnostic kits are used on at least 1·5 million people with suspected tuberculosis every year. Such testing is not done through the Revised National TB Control Programme (RNTCP) but through the unregulated private sector, which manages a substantial proportion of tuberculosis cases. Patients pay for serodiagnostic kits, and the market is estimated conservatively at over $US15 million in India alone, compared with $65 million for the entire RNTCP.
Despite country-wide DOTS coverage by the RNTCP, India continues to have more than 2 million new cases of tuberculosis every year. Ongoing transmission will not be reduced without intensified early case detection, which first relies on access to quality diagnosis. Writing in The New Yorker on Nov 15, journalist Michael Specter described how, in India, “for most patients, the choices are bleak”—overcrowded public hospitals versus unreliable tests at unregulated private laboratories or clinics.
Everyone in the private-sector chain gets a cut of patient fees—up to $10—30 per serodiagnostic kit—especially the referring doctors and private clinicians, who are often the same individual, Specter reports. Financial incentives perpetuate this system, Pai explains, since: “a private practitioner may not order sputum microscopy because you don't make much money out of a cheap test like sputum smears. The more expensive the test ordered, the more money you get back”, he explains.
The available evidence indicates that current tests lack either the necessary sensitivity or specificity or both to be an effective diagnostic test, and for many of these tests, false results far outnumber true results. Low sensitivity means increased false-negative results, which increase morbidity, mortality, and ongoing transmission of tuberculosis. Low specificity means more false-positive results; patients might then be given 6 months of potentially toxic treatment, while their underlying pathology remains uninvestigated and undiagnosed.
Atul Loke/Panos India has more than 2 million new cases of tuberculosis every year
Many commercial tuberculosis serology kits are manufactured in China or India, but some are from western countries, such as France, the UK, Canada, and the USA. These manufacturers are selling high volumes of their test kits in countries such as India, although their tests are not licensed or used in the countries that make them.
During WHO's systematic review process, says Weyer, “we quickly discovered that manufacturers of these commercial serodiagnostics simply change the name of the test frequently and re-market and re-sell the same test under a new brand name. So, teasing out which test belonged to which brand name and updating the previous review by TDR proved to be a real challenge, as we wanted to be as solid as we could possibly be on the actual evidence.”
The key question is how much will the WHO guidance affect the sale and use of these tests in the private sector? “The ideal is that the public sector would be attractive enough and use state-of-the-art new tests, so that patients don't feel that they need to go to the private sector to get what they think may be a better diagnosis”, says Weyer.
However, given the extent of private-sector medicine, the concept of public—private mix (PPM) is being hailed in some quarters as the key to increasing efforts to tackle tuberculosis. The final report of WHO's subgroup on PPM for tuberculosis care and control advised earlier this year that countries need to scale up PPM, and involve provider groups outside national programmes to develop national strategic plans. Recommended approaches also include certification and accreditation of care providers and laboratories, and a system for mandatory notification of tuberculosis.
To achieve PPM recommendations, regulation of private-sector medicine will need to be developed and implemented in high-burden countries. What is absent from the PPM report is recognition that regulatory frameworks for diagnostic tests are also often weak or non-existent. WHO is helping countries establish regulatory systems to review the local relevance of diagnostics, and determine whether such tests should be marketed and sold, says Weyer. But, she foresees “a long-term difficult process”, as local expertise and capacity are often limited and regulatory frameworks need to be drawn up and passed through national legal systems country by country.
“Public-private partnership is the way to go”, asserts Camilla Rodrigues, a physician at the private Hinduja Hospital, in Mumbai, India, who has trialled the Xpert MTB/RIF system for diagnosis and drug-resistance testing of tuberculosis for more than 3 years. Rodrigues would like to see physician education on the unreliability of serology in endemic regions and laboratory accreditation encouraged. National governments need to provide guidelines for tuberculosis testing with “strict regulation in place for defaulters”, she says, adding that laboratories need diagnostic algorithms and strengthened capacity both for gold-standard tests, such as culture, and validated new molecular tests.
Weyer agrees, but notes that: “PPM alone will not overcome barriers presented by the lack of country regulatory frameworks for new diagnostics”. Nevertheless, market forces could play a part in developing and implementing better tuberculosis diagnostics. If Xpert MTB/RIF or other technologies are developed to become point-of-care tests, the private sector already has the infrastructure to deliver, and effective diagnostics could successfully replace inaccurate tests, says Pai.
The chief executive of a large private Indian diagnostic laboratory chain, Sanjeev Chaudhry, told The Lancet that Super Religare Laboratories strongly concurs in discouraging use of serodiagnostic kits in Indian settings. However, mere policy change might not be effective with the current magnitude of the challenge, he says, so, “instead of change in policy by private lab(s) in isolation or even as a consortium, we seriously feel that collective and dedicated efforts are required equally by the public- and private-sector service providers”.
As pathology service providers are expected to offer and satisfy the needs of the market, Chaudry continues that “we need to have an alternative cost-effective option along with appropriate awareness among clinicians and doctors”. Rodrigues notes that “the Indian diagnostic market is thriving. There is certainly potential for low-cost, accurate, and newer tests to be produced in India which will lower the cost.”
WHO guidance will be very clear, Weyer confirms, “to reflect the current commercial serodiagnostic tests but not to jeopardise future research and new antigen and biomarker discovery programmes that would guide and inform the development of point-of-care tests”.
http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2811%2960005-6/fulltext?rss=yes
TUBERCULOSIS: A comparative examination of tuberculosis immigration medical screening programs from selected countries with high immigration and low tuberculosis incidence rates
Author: Gonzalo Alvarez et al. Tuberculosis (TB) in migrants is an ongoing challenge in several low TB incidence countries since a large proportion of TB in these countries occurs in migrants from high incidence countries. To meet these challenges, several countries utilize TB screening programs.
The programs attempt to identify and treat those with active and/or infectious stages of the disease. In addition, screening is used to identify and manage those with latent or inactive disease after arrival.
Between nations, considerable variation exists in the methods used in migration-associated TB screening. The present study aimed to compare the TB immigration medical examination requirements in selected countries of high immigration and low TB incidence rates.
Methods:
Descriptive study of immigration TB screening programs
Results:
16 out of 18 eligible countries responded to the written standardized survey and phone interview.
Comparisons in specific areas of TB immigration screening programs included authorities responsible for TB screening, the primary objectives of the TB screening program, the yield of detection of active TB disease, screening details and aspects of follow up for inactive pulmonary TB. No two countries had the same approach to TB screening among migrants.
Important differences, common practices, common problems, evidence or lack of evidence for program specifics were noted.
Conclusions:
In spite of common goals, there is great diversity in the processes and practices designed to mitigate the impact of migration-associated TB among nations that screen migrants for the disease. The long-term goal in decreasing migration-related introduction of TB from high to low incidence countries remains diminishing the prevalence of the disease in those high incidence locations.
In the meantime, existing or planned migration screening programs for TB can be made more efficient and evidenced based. Cooperation among countries doing research in the areas outlined in this study should facilitate the development of improved screening programs.
http://7thspace.com/headlines/368603/a_comparative_examination_of_tuberculosis_immigration_medical_screening_programs_from_selected_countries_with_high_immigration_and_low_tuberculosis_incidence_rates.html
The programs attempt to identify and treat those with active and/or infectious stages of the disease. In addition, screening is used to identify and manage those with latent or inactive disease after arrival.
Between nations, considerable variation exists in the methods used in migration-associated TB screening. The present study aimed to compare the TB immigration medical examination requirements in selected countries of high immigration and low TB incidence rates.
Methods:
Descriptive study of immigration TB screening programs
Results:
16 out of 18 eligible countries responded to the written standardized survey and phone interview.
Comparisons in specific areas of TB immigration screening programs included authorities responsible for TB screening, the primary objectives of the TB screening program, the yield of detection of active TB disease, screening details and aspects of follow up for inactive pulmonary TB. No two countries had the same approach to TB screening among migrants.
Important differences, common practices, common problems, evidence or lack of evidence for program specifics were noted.
Conclusions:
In spite of common goals, there is great diversity in the processes and practices designed to mitigate the impact of migration-associated TB among nations that screen migrants for the disease. The long-term goal in decreasing migration-related introduction of TB from high to low incidence countries remains diminishing the prevalence of the disease in those high incidence locations.
In the meantime, existing or planned migration screening programs for TB can be made more efficient and evidenced based. Cooperation among countries doing research in the areas outlined in this study should facilitate the development of improved screening programs.
http://7thspace.com/headlines/368603/a_comparative_examination_of_tuberculosis_immigration_medical_screening_programs_from_selected_countries_with_high_immigration_and_low_tuberculosis_incidence_rates.html
TUBERCULOSIS: A faster way to screen patients for tuberculosis
Vimita Mohandas Jan 07, 2011
SINGAPORE - Screening for tuberculosis (TB) involves several time-consuming procedures. But researchers from Ngee Ann Polytechnic's School of Engineering and SATA CommHealth have invented a faster method to detect the disease. Using a software programme, it will take just minutes as the texture of the lungs in X-rays is analysed.
Dr Rajendra Acharya, from Ngee Ann Poly's Diploma in Biomedical Engineering programme, said the new method is fast when compared with the current method where culture tests are done on the patient and the radiologist has to examined all the X-rays.
The team says it has achieved a 90 per cent success rate in accurately detecting the incidence of TB in patients since they started their research in November.
It hopes to achieve a 100 per cent success rate in about one-and-a-half years. SATA CommHealth'sDiagnostic Imaging Services Manager, Mr Collin Tan, hopes this new computer-aided tool would help to improve the efficiency of radiologists.
He said: "Currently, we are doing around 16,000 chest X-rays per month and we have only two radiologists reporting chest X-rays. With this tool, we hope it would help radiologists filter out suspected TB cases and improve their productivity." Vimita Mohandas
http://www.todayonline.com/Singapore/EDC110107-0000207/A-faster-way-to-screen-patients-for-tuberculosis
SINGAPORE - Screening for tuberculosis (TB) involves several time-consuming procedures. But researchers from Ngee Ann Polytechnic's School of Engineering and SATA CommHealth have invented a faster method to detect the disease. Using a software programme, it will take just minutes as the texture of the lungs in X-rays is analysed.
Dr Rajendra Acharya, from Ngee Ann Poly's Diploma in Biomedical Engineering programme, said the new method is fast when compared with the current method where culture tests are done on the patient and the radiologist has to examined all the X-rays.
The team says it has achieved a 90 per cent success rate in accurately detecting the incidence of TB in patients since they started their research in November.
It hopes to achieve a 100 per cent success rate in about one-and-a-half years. SATA CommHealth'sDiagnostic Imaging Services Manager, Mr Collin Tan, hopes this new computer-aided tool would help to improve the efficiency of radiologists.
He said: "Currently, we are doing around 16,000 chest X-rays per month and we have only two radiologists reporting chest X-rays. With this tool, we hope it would help radiologists filter out suspected TB cases and improve their productivity." Vimita Mohandas
http://www.todayonline.com/Singapore/EDC110107-0000207/A-faster-way-to-screen-patients-for-tuberculosis
Monday, 3 January 2011
TUBERCULOSIS: Long Delays and Missed Opportunities in Diagnosing Smear-Positive Pulmonary Tuberculosis in Kampala, Uganda: A Cross-Sectional Study
December 30, 2010 Early detection and treatment of tuberculosis cases are the hallmark of successful tuberculosis control. We conducted a cross-sectional study at public primary health facilities in Kampala city, Uganda to quantify diagnostic delay among pulmonary tuberculosis (PTB) patients, assess associated factors, and describe trajectories of patients’ health care seeking.
Methodology/Principal Findings
Semi-structured interviews with new smear-positive PTB patients (≥15 years) registered for treatment. Between April 2007 and April 2008, 253 patients were studied. The median total delay was 8 weeks (IQR 4–12), median patient delay was 4 weeks (inter-quartile range [IQR] 1–8) and median health service delay was 4 weeks (IQR 2–8). Long total delay (>14 weeks) was observed for 61/253 (24.1%) of patients, long health service delay (>6 weeks) for 71/242 (29.3%) and long patient delay (>8 weeks) for 47/242 (19.4%). Patients who knew that TB was curable were less likely to have long total delay (adjusted Odds Ratio [aOR] 0.28; 95%CI 0.11–0.73) and long patient delay (aOR 0.36; 95%CI 0.13–0.97). Being female (aOR 1.98; 95%CI 1.06–3.71), staying for more than 5 years at current residence (aOR 2.24 95%CI 1.18–4.27) and having been tested for HIV before (aOR 3.72; 95%CI 1.42–9.75) was associated with long health service delay. Health service delay contributed 50% of the total delay. Ninety-one percent (231) of patients had visited one or more health care providers before they were diagnosed, for an average (median) of 4 visits (range 1–30). All but four patients had systemic symptoms by the time the diagnosis of TB was made.
Conclusions/Significance
Diagnostic delay among tuberculosis patients in Kampala is common and long. This reflects patients waiting too long before seeking care and health services waiting until systemic symptoms are present before examining sputum smears; this results in missed opportunities for diagnosis.
http://elitestv.com/pub/2010/12/long-delays-and-missed-opportunities-in-diagnosing-smear-positive-pulmonary-tuberculosis-in-kampala-uganda-a-cross-sectional-study
Methodology/Principal Findings
Semi-structured interviews with new smear-positive PTB patients (≥15 years) registered for treatment. Between April 2007 and April 2008, 253 patients were studied. The median total delay was 8 weeks (IQR 4–12), median patient delay was 4 weeks (inter-quartile range [IQR] 1–8) and median health service delay was 4 weeks (IQR 2–8). Long total delay (>14 weeks) was observed for 61/253 (24.1%) of patients, long health service delay (>6 weeks) for 71/242 (29.3%) and long patient delay (>8 weeks) for 47/242 (19.4%). Patients who knew that TB was curable were less likely to have long total delay (adjusted Odds Ratio [aOR] 0.28; 95%CI 0.11–0.73) and long patient delay (aOR 0.36; 95%CI 0.13–0.97). Being female (aOR 1.98; 95%CI 1.06–3.71), staying for more than 5 years at current residence (aOR 2.24 95%CI 1.18–4.27) and having been tested for HIV before (aOR 3.72; 95%CI 1.42–9.75) was associated with long health service delay. Health service delay contributed 50% of the total delay. Ninety-one percent (231) of patients had visited one or more health care providers before they were diagnosed, for an average (median) of 4 visits (range 1–30). All but four patients had systemic symptoms by the time the diagnosis of TB was made.
Conclusions/Significance
Diagnostic delay among tuberculosis patients in Kampala is common and long. This reflects patients waiting too long before seeking care and health services waiting until systemic symptoms are present before examining sputum smears; this results in missed opportunities for diagnosis.
http://elitestv.com/pub/2010/12/long-delays-and-missed-opportunities-in-diagnosing-smear-positive-pulmonary-tuberculosis-in-kampala-uganda-a-cross-sectional-study
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