Tuberculosis causes more deaths globally than any other infectious disease and is a top 10 cause of death worldwide. When it is detected early and effectively treated, tuberculosis is largely curable. In 2018, around 10 million people developed tuberculosis disease (similar to the number in the past several years). In 2018, around 1.2 million HIV-negative people died from tuberculosis (a 27% decrease from 1.7 million in 2000), and around 251,000 HIV-positive people died from tuberculosis (a 60% decrease from 620,000 in 2000). In addition, there were approximately half a million new cases of rifampicin-resistant tuberculosis, with India (27%), China (14%) and the Russian Federation (9%) accounting for the largest burden. Early diagnosis of tuberculosis, including universal drug susceptibility testing and systematic screening of contacts and high-risk groups, is part of pillar one of the World Health Organization (WHO)’s "End TB" strategy.
The global effort against tuberculosis is currently being ramped up as the world enters a new era in the fight against tuberculosis. In May 2018, the WHO published the first Essential Diagnostics List, and in September 2018, the United Nations held its first ever High-Level Meeting on ending tuberculosis, galvanizing a global commitment to end the disease by 2030. The High-Level Meeting was the culmination of intensive joint work and collaboration that began with the WHO Global Ministerial Conference on Ending TB in Moscow in November 2017.
The next several years will be critical to ensure this momentum is translated into an accelerated response to End TB. The commitment from the UN High-Level Meeting to finding and treating 40 million people with tuberculosis, including 3.5 million children and 1.5 million people with drug-resistant tuberculosis, as well as providing preventive treatment to 30 million individuals by 2022, should help to focus efforts.
The WHO Global TB Programme has, for the last decade, led the development of guidelines for diagnostic tests that allow for early and rapid detection of tuberculosis and drug-resistant tuberculosis. However, sputum smear microscopy remains the primary diagnostic technique in many high tuberculosis burden settings, despite being a relatively insensitive test. Microscopy as the initial diagnostic test should be replaced with WHO-recommended rapid diagnostics described in this Special Collection.
This Special Collection, curated by Cochrane contributors, includes Cochrane Reviews from the Cochrane Infectious Diseases Group and other systematic reviews from other international teams. It highlights how Cochrane evidence contributes within a wider landscape of tuberculosis evidence and guidelines. The Collection also describes key WHO guidelines on tuberculosis diagnostics, and their underpinning systematic reviews, some which are published within the WHO Guideline itself.
This Special Collection covers:
- Early detection of tuberculosis
- Diagnosis of active tuberculosis disease and tuberculosis drug resistance
- Diagnosis of tuberculosis in people living with HIV
- Diagnosis of tuberculosis in children
- Diagnosis of latent tuberculosis infection.
You can browse the full list of Cochrane Reviews related to diagnosing tuberculosis, and you can read WHO's Compendium of WHO guidelines and associated standards: ensuring optimum delivery of the cascade of care for patients with tuberculosis. You may also find it useful to refer to the Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention clinical practice guidelines on diagnosis of tuberculosis, which are based on comprehensive evidence syntheses.
Kathryn Lougheed writes: "Untangling ourselves from this foe is not a simple task. How do you kill something that’s spent millions of generations finding ways not to be killed? … Because if we can understand the makings of TB, then maybe we can find a way to unmake it". We hope this Special Collection of WHO guidelines and systematic reviews on TB diagnosis will enable anyone who is interested to find high-quality information easily and improve understanding of TB diagnosis. Then, we will find the way to unmake it.
This Special Collection is curated by Karen Steingart (Editor, Cochrane Infectious Diseases), Alexei Korobitsyn (Technical Officer, Laboratories, Diagnostics & Drug Resistance, Global Tuberculosis Programme, World Health Organization), Mikashmi Kohli (Author, Cochrane Infectious Diseases), and Paul Garner (Co-ordinating Editor, Cochrane Infectious Diseases). We are grateful to Christopher Gilpin (Global Laboratory Coordinator, Migration Health Division, International Organization for Migration) for his help with the original version of this collection.
Early detection of tuberculosis
Early detection of tuberculosis helps reduce the severity of illness and minimize the spread of infection. The WHO, along with its partners, developed a guideline on screening for active tuberculosis. Key principles of the guideline are to prioritize risk groups and avoid indiscriminate mass screening. People with very high risk of tuberculosis or severe consequences of delayed tuberculosis diagnosis should be prioritized first. The WHO defines screening for active tuberculosis as “the systematic identification of people with suspected active tuberculosis, in a predetermined target group, using tests, examinations or other procedures that can be rapidly applied”.
This Cochrane protocol outlines a review in progress, which will assess the sensitivity and specificity of questioning people about the presence of one or more symptoms, chest X-ray abnormalities, and various combinations of symptoms and chest X-ray abnormalities for detecting microbiologically-confirmed active pulmonary tuberculosis in HIV-negative people and people with unknown HIV status considered for tuberculosis screening. A report from some initial analyses of these studies was used in the development of a WHO guideline: Systematic screening for active tuberculosis: principles and recommendations. An updated WHO policy review on tuberculosis screening will take place later in 2020 and include recommendations for tuberculosis screening in adults and children.
Diagnosis of active tuberculosis disease and tuberculosis drug resistance
Rapid, accurate, and accessible diagnostic tests provide obvious benefits for patients (earlier diagnosis and the opportunity to begin earlier, appropriate treatment) and for public health (opportunities to interrupt tuberculosis transmission), especially in countries with a high tuberculosis burden.
Xpert MTB/RIF and Xpert Ultra, the newest version, are WHO-recommended rapid tests that simultaneously detect tuberculosis and rifampicin resistance in people with signs and symptoms of tuberculosis and are suitable for use at lower levels of the health system. This Cochrane Review assesses the diagnostic accuracy of Xpert MTB/RIF and Xpert Ultra for active pulmonary TB in adults. This work is associated with the WHO guideline Xpert MTB/RIF assay for the diagnosis of pulmonary and extrapulmonary TB in adults and children and the WHO Meeting Report of a Technical Expert Consultation: non-inferiority analysis of Xpert MTB/RIF Ultra compared to Xpert MTB/RIF, and policy update (2020): See: Molecular assays intended as initial tests for the diagnosis of pulmonary and extrapulmonary TB and rifampicin resistance in adults and children: rapid communication.
This diagnostic accuracy study comparing Xpert MTB/RIF Ultra (Ultra), the newest generation of the test, with Xpert MTB/RIF, informed the WHO Technical Consultation. The study found Ultra to be non-inferior to Xpert MTB/RIF for the detection of TB and rifampicin resistance. This means that Ultra is at least as good as Xpert MTB/RIF. Ultra had higher sensitivity than Xpert MTB/RIF, in particular in smear-negative, culture-positive specimens and in specimens from HIV-positive patients. However, the increase in sensitivity was accompanied by a decrease in specificity. Ultra and Xpert MTB/RIF had similar accuracy for rifampicin resistance. The current WHO recommendations for the use of Xpert MTB/RIF now also apply to the use of Ultra as the initial diagnostic test for all adults and children with signs and symptoms of TB and in the testing of selected extrapulmonary specimens (cerebrospinal fluid, lymph nodes, and tissue specimens). See: Molecular assays intended as initial tests for the diagnosis of pulmonary and extrapulmonary TB and rifampicin resistance in adults and children: rapid communication.
Extrapulmonary TB accounts for 15% to 20% of tuberculosis cases, but the percentage is increasing. This review assessed the diagnostic accuracy of Xpert MTB/RIF for detection of extrapulmonary tuberculosis. This review informed the WHO recommendations on the use of Xpert MTB/RIF in the testing of selected extrapulmonary specimens (cerebrospinal fluid, lymph nodes, and tissue specimens). See Xpert MTB/RIF assay for the diagnosis of pulmonary and extrapulmonary TB in adults and children and WHO Meeting Report of a Technical Expert Consultation: non-inferiority analysis of Xpert MTB/RIF Ultra compared to Xpert MTB/RIF.
This Cochrane Review assessed the diagnostic accuracy of Xpert MTB/RIF in extrapulmonary specimens and included eight forms of extrapulmonary tuberculosis: tuberculous meningitis; pleural tuberculosis; lymph node tuberculosis; bone or joint tuberculosis; genitourinary tuberculosis; peritoneal tuberculosis, pericardial tuberculosis; and disseminated tuberculosis. Earlier versions of this review were used by the Indian Government's Revised National Tuberculosis Control Program in drawing up national guidelines for detection and management of extrapulmonary tuberculosis: Index-TB Guidelines: guidelines for extra-pulmonary tuberculosis for India , and policy update (2020): Molecular assays intended as initial tests for the diagnosis of pulmonary and extrapulmonary TB and rifampicin resistance in adults and children: rapid communication.
Accurate diagnosis of tuberculosis in people living with HIV is difficult. HIV‐positive individuals have higher rates of extrapulmonary tuberculosis, and the diagnosis of tuberculosis is often limited to imaging results. Ultrasound is an imaging test that is widely used as a diagnostic tool in people suspected of having abdominal tuberculosis or disseminated tuberculosis with abdominal involvement. This review assessed how accurate an ultrasound examination of the abdomen (abdominal ultrasound) is for diagnosing tuberculosis in people with HIV suspected of having tuberculosis in the abdomen or widespread tuberculosis (disseminated tuberculosis) involving the abdomen.
Line probe assays are rapid molecular diagnostic tests for detecting TB and TB drug resistance. Owing to their complexity, line probe assays are used in reference and regional laboratories and take longer to run than the Xpert MTB/RIF assay. However, unlike Xpert MTB/RIF, which only detects rifampicin resistance, these assays have the ability to detect isoniazid resistance in addition to rifampicin resistance. Rifampicin and isoniazid are two of the most effective and widely-used anti-TB drugs that form part of the standardized first-line regimen for drug-susceptible TB. This review assessed the diagnostic accuracy of line probe assays for detection of TB and resistance to rifampicin and isoniazid, and it informed a WHO process to develop updated guidelines on the use of these tests: The use of molecular line probe assays for the detection of resistance to isoniazid and rifampicin.
People with drug-resistant tuberculosis require second-line tuberculosis drugs that, compared with first-line tuberculosis drugs, must be taken for longer and may be associated with more harms. Detecting tuberculosis drug resistance quickly is important for improving health, reducing deaths, and decreasing the spread of drug-resistant tuberculosis. Genotype MTBDRsl is a rapid DNA-based test for detecting specific mutations associated with resistance to fluoroquinolones and second-line injectable drugs in Mycobacterium tuberculosis complex. MTBDRsl belongs to a category of molecular genetic tests called line probe assays. MTBDRsl version 2.0 (released in 2015) identifies the mutations detected by version 1.0, as well as additional mutations. The test may be performed on a culture isolate or a patient specimen, which eliminates delays associated with culture. Version 1.0 requires a smear-positive specimen, while version 2.0 may use a smear-positive or -negative specimen. This updated review informed a WHO process to develop updated guidelines for using MTBDRsl: The use of molecular line probe assays for the detection of resistance to second-line anti-tuberculosis drugs.
Commercial serological tests, which detect antibodies against Mycobacterium tuberculosis in the blood, could provide a way to diagnose TB in resource-limited countries. There has been uncertainty, however, about the accuracy of these tests. This review assessed the diagnostic accuracy of commercial serological tests for pulmonary and extrapulmonary TB, and is associated with the WHO guideline on Commercial serodiagnostic tests for diagnosis of tuberculosis.
This review, including 443 studies, summarizes evidence on proposed biomarkers and biosignatures. Please note, this content is not Open Access. Supporting data can be found at Bm2Dx: The Biomarker Database.
Diagnosis of tuberculosis in people living with HIVGlobally in 2018, an estimated 10 million people developed tuberculosis disease, including an estimated 860,000 people living with HIV. Tuberculosis remains a leading cause of hospitalization and in-hospital death among adults and children living with HIV, despite increased access to antiretroviral therapy. According to the WHO, around 50% of all people with HIV-associated tuberculosis did not reach care. Reducing deaths in HIV-positive people will require new, sensitive, point-of-care tests, which can be applied in the community and in primary healthcare facilities.
This review aimed at identifying a standardized TB screening rule for use with HIV-positive people living in resource-limited settings. The rule would distinguish people who are unlikely to have TB from those who require further evaluation for TB disease. The related WHO guideline is Consolidated guidelines on the use of antiretroviral drugs for treating and preventing HIV infection.
The lateral flow urine lipoarabinomannan (LF‐LAM) assay Alere Determine™ TB LAM Ag is recommended by the World Health Organization (WHO) to help detect active tuberculosis in HIV‐positive people. This review update asks if the new evidence justifies the use of LF‐LAM in a broader group of people, and is part of the WHO process for updating guidance on the use of LF‐LAM. This review assesses the accuracy of LF‐LAM for the diagnosis of active tuberculosis among HIV‐positive adults with signs and symptoms of tuberculosis (symptomatic participants) and among HIV‐positive adults irrespective of signs and symptoms of tuberculosis (unselected participants not assessed for tuberculosis signs and symptoms). Current WHO guideline: The use of lateral flow urine lipoarabinomannan assay (LF-LAM) for the diagnosis and screening of active tuberculosis in people living with HIV.
This protocol outlines a systematic review to assess the accuracy of the four-symptom screen (cough, fever, night sweats, or weight loss) for identifying active tuberculosis in pregnant women living with HIV who are screened in an outpatient or community setting.
Diagnosis of tuberculosis in childrenAccording to the WHO, globally in 2018, an estimated one million children under 15 years of age developed tuberculosis and 230,000 children (including children with HIV-associated tuberculosis) died from the disease, although many believe these estimates are too low. The diagnosis of tuberculosis in children relies on clinical, epidemiological, radiological, and laboratory information. Child tuberculosis is typically paucibacillary (tuberculosis disease caused by a smaller number of bacteria) and young children cannot voluntarily produce sputum specimens. Therefore, even under ideal clinical and laboratory conditions, only 30% to 40% of children with tuberculosis are microbiologically confirmed. Child tuberculosis needs to be lifted "out of the shadows". New tuberculosis tests are urgently needed for children.
This review assessed the diagnostic accuracy of Xpert MTB/RIF assay compared with microscopy for pulmonary TB in children and informed the WHO recommendations on the use of Xpert MTB/RIF in children. The related WHO guidelines are Xpert MTB/RIF assay for the diagnosis of pulmonary and extrapulmonary TB in adults and children and WHO Meeting Report of a Technical Expert Consultation: non-inferiority analysis of Xpert MTB/RIF Ultra compared to Xpert MTB/RIF.
This protocol outlines a systematic review update (in progress) to the previous review, the objective being to determine the accuracy of the Xpert MTB/RIF and Xpert Ultra in symptomatic children for diagnosing pulmonary tuberculosis, tuberculous meningitis, lymph node tuberculosis, and rifampicin resistance. The related WHO guideline (2020 update) is: Molecular assays intended as initial tests for the diagnosis of pulmonary and extrapulmonary TB and rifampicin resistance in adults and children: rapid communication.
Stool is a promising specimen for diagnosing tuberculosis in children, because stool collection is non-invasive. Its greatest benefit may be in young children owing to the challenges of collecting specimens through sputum induction and gastric aspiration in this population. This review determines the diagnostic accuracy of Xpert MTB/RIF for tuberculosis in stool specimens in children.
Diagnosis of latent tuberculosis infection
Around one-fourth to one-third of the world’s population is infected with Mycobacterium tuberculosis, though most people do not feel ill, do not have signs or symptoms of TB disease, and cannot spread TB to others. The related WHO guideline is: Latent TB infection: updated and consolidated guidelines for programmatic management. The guideline defines latent TB infection as "a state of persistent immune response to stimulation by Mycobacterium tuberculosis antigens with no evidence of clinically manifest active TB". People with TB infection have a 5% to 15% risk of progressing to active TB disease in their lifetime, with the risk of progression being highest in the first two years after acquiring TB infection. The key principle in developing these updated guidelines was "individual benefit should outweigh risk as the mainstay of recommendations on latent TB infection testing and treatment".
This review investigated the use of the WHO-recommended four-symptom screen (cough, fever, night sweats, or weight loss), for people living with HIV on antiretroviral therapy compared with those not taking antiretroviral therapy, to exclude active tuberculosis before starting preventive treatment.
This review aimed to assess whether interferon-gamma release assays can predict the development of active tuberculosis and whether the ability of interferon-gamma release assays for prediction was higher than that of the tuberculin skin test.
This review aimed to assess whether the use of interferon-gamma release assays could improve the identification of HIV-positive people who could benefit from tuberculosis preventive treatment.
- World Health Organization. Global tuberculosis report 2018. www.who.int/tb/publications/global_report (accessed 15 March 2019).
- World Health Organization. Compendium of WHO guidelines and associated standards: ensuring optimum delivery of the cascade of care for patients with tuberculosis. 2nd Edition. WHO: 2018. Available at www.who.int/tb/publications/Compendium_WHO_guidelines_TB_2017
- Lewinsohn DM, Leonard MK, LoBue PA, Cohn DL, Daley CL, Desmond E, et al. Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention clinical practice guidelines: diagnosis of tuberculosis in adults and children. Clinical Infectious Diseases 2017;64:111-5. https://doi.org/10.1093/cid/ciw778
- Lougheed K. Catching Breath: The Making and Unmaking of Tuberculosis. London (UK): Bloomsbury Publishing, 2017.
- Sharma SK, Ryan H, Khaparde S, Sachdeva KS, Singh AD, Mohan A, et al. Index-TB guidelines: guidelines on extrapulmonary tuberculosis for India. Indian Journal of Medical Research 207;145(4):448-63. www.ncbi.nlm.nih.gov/pmc/articles/PMC5663158
- Ford N, Matteelli A, Shubber Z, Hermans S, Meintjes G, Grinsztejn B, et al. TB as a cause of hospitalization and in-hospital mortality among people living with HIV worldwide: a systematic review and meta-analysis. Journal of the International AIDS Society 2016;19(1):20714. https://doi.org/10.7448/IAS.19.1.20714
- Goosby E. Out of the shadows: shining a light on children with tuberculosis. International Journal of Tuberculosis and Lung Disease 2015;19 Suppl 1:S1-2. https://doi.org/10.5588/ijtld.15.0411
- World Health Organization. Systematic screening for active tuberculosis. Principles and recommendations. Geneva.: World Health Organization., 2013:1‐146. http://apps.who.int/iris/bitstream/10665/84971/1/9789241548601_eng.pdf
Karen Steingart, Alexei Korobitsyn, Christopher Gilpin, Mikashmi Kohli, and Paul Garner drafted the text and selected the reviews. This publication is associated with the Research, Evidence and Development Initiative (READ-It) project. READ-It (project number 300342-104) is funded by UK aid from the UK government; however, the views expressed do not necessarily reflect the UK government’s official policies.
The Global Fund/Jonas Gratzer
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