Tuberculosis (TB)

Global Task Force on TB Impact Measurement

Who are we?

In June 2006, the Global TB Programme (GTB) in the World Health Organization (WHO) established a Global Task Force on TB Impact Measurement, with the TB monitoring and evaluation unit in GTB acting as the secretariat.

The Task Force includes a wide range of experts in TB epidemiology, statistics and modelling, representatives from major technical and financial partners and representatives from countries with a high burden of TB.

The initial aim of the Task Force was to ensure that WHO’s assessment of whether 2015 global TB targets were achieved was as rigorous, robust and consensus-based as possible. Following publication of this assessment in the 2015 Global TB Report and in the context of the End TB Strategy (2016-2035) and the Sustainable Development Goals (2016-2030), the Task Force reviewed and updated its mandate and strategic areas of work for the post-2015 era in April 2016.

What is our mandate?

The Task Force's mandate for the period 2016-2020 is:

  • To ensure that assessments of progress towards the End TB Strategy and United Nations Sustainable Development Goals targets and milestones at global, regional and country levels are as rigorous, robust and consensus-based as possible.

  • To guide, promote and support the analysis and use of TB data for policy, planning, and programmatic action.

The 2020 milestones of the End TB strategy are a 35% reduction in TB deaths and a 20% reduction in the TB incidence rate compared with levels in 2015, and that no TB patients and their households face catastrophic costs as a result of TB disease.

Strategic areas of work, 2016-2020

  • Strengthening national notification systems for direct measurement of TB cases, including drug-resistant TB and HIV-associated TB specifically. [More]

  • Strengthening national vital registration systems for direct measurement of TB deaths. [More]

  • Priority studies to periodically measure TB disease burden. These include (but are not limited to):
    • National TB prevalence surveys. [More]
    • Drug resistance surveys. [More]
    • Mortality surveys. [More]
    • Surveys of costs faced by TB patients and their households. [More]

  • Periodic review of methods used by WHO to estimate the burden of TB disease and latent TB infection. [More]

  • Analysis and use of TB data at country level. This includes:
    • Disaggregated analyses (e.g. by age, sex, location) to assess inequalities and equity.
    • Projections of disease burden and intervention impact.
    • Guidance, tools and capacity building. [More]

Details on strategic areas of work

1. Strengthening national notification systems for direct measurement of TB cases

  • TB epidemiological reviews, including the use of the WHO TB surveillance checklist.
  • Regional analysis workshops.
  • Transitioning from paper to digital case-based surveillance.
  • TB inventory studies to measure under-reporting of detected TB cases.

Between January 2013 and April 2019, 75 countries completed the TB surveillance checklist and a TB epidemiological review:

Map: countries where TB epidemiological reviews have been carried out (2013-2019)

Estimates of TB incidence rely on the systematic analysis of case notification and programmatic data combined with assessment of the number of cases not reported and not diagnosed. The Assessing tuberculosis under-reporting through inventory studies guide describes and explains how to design, implement and analyse inventory studies to measure the under-reporting of detected TB cases.

Inventory studies are now being promoted in selected countries, linked to recommendations following TB epidemiological reviews and use of the TB surveillance checklist. They are of particular relevance in countries with large private sectors or where large numbers of TB patients are thought to be treated in the public sector but not reported to national authorities.

By the end of 2018, a national inventory study had been completed in 16 countries. Inventory studies have started in China, South Africa and Tanzania and are planned in Armenia, the Philippines and Ukraine:

Map of countries: TB inventory studies (2019)

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2. Strengthening national vital registration (VR) systems systems for direct measurement of TB deaths

  • Promote use of VR data for measurement of TB deaths.
  • Create and sustain links with relevant stakeholders.
  • Mortality studies to validate VR data.

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3. Studies to periodically measure TB disease burden

National TB prevalence surveys

Map of countries: TB prevalence surveys (2007 - 2019)

Between 2009 and 2018, national surveys of the prevalence of TB disease were implemented in 27 countries, following guidance in the Tuberculosis prevalence surveys handbook (2nd ed: the “lime book”) developed by the Task Force.

Myanmar (repeat survey), Namibia and Viet Nam (repeat survey) completed field operations in 2018. Results are expected by mid-2019. Eswatini, Mozambique, Nepal and South Africa plan to finish their surveys in 2019. India is planning to start a survey in 2019.

In 2016, the Task Force recommended the following criteria for implementing a national TB prevalence survey: a country had already conducted a survey between 2007 and 2015; or an estimated incidence of ≥150 per 100,000 population per year, no nationwide vital registration system with standard coding of causes of deaths and an infant mortality rate >10/1000 live births.

Numerous country missions and workshops have been used to facilitate inter-country collaboration and boost capacity to design and implement high-quality surveys and to analyse and report results according to best-practice standards.

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Surveys of anti-TB drug resistance

The Global Project on Anti-TB Drug Resistance Surveillance was launched in 1994. It aims to estimate the magnitude of drug resistance among TB patients and determine trends over time. Approaches to surveillance are outlined in the Guidelines for surveillance of drug resistance in tuberculosis (5th ed: 2015).

In 2017, 7 countries completed a drug resistance survey (DRS). Eritrea, Indonesia and Lao People's Democratic Republic, completed their first nationwide survey, and Eswatini, Sri Lanka, Togo and the United Republic of Tanzania completed a repeat survey.

By April 2019, data from continuous national surveillance systems based on routine drug susceptibility testing of TB patients were available from 91 countries, and 77 countries had implemented at least one nationally representative (or subnational) survey since 1994. In April 2019, 19 countries were implementing a survey:

Map of countries: TB drug resistance surveys (up to 2019)

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Mortality surveys

Mortality surveys can be used to provide a direct measurement of TB deaths in countries without national vital registration systems of sufficient quality and coverage. They can also be used to validate the quality of data compiled in national vital registration systems.

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Patient and household cost surveys

Map of countries: patient and household cost surveys (2016 - 2019)

The Tuberculosis patient cost surveys: a handbook was developed to support countries to conduct nationally representative surveys of costs faced by TB patients and their households, and to assess whether these costs are catastrophic. The surveys inform policy discussions on how to improve TB services and their financing, and how to advance universal health coverage and enhance social protection, with the overall aim of achieving the target that no TB patients and their households face catastrophic costs due to TB.

By early 2019, 13 countries had completed a survey (China, Fiji, Ghana, Kenya, Myanmar, Mongolia, Nigeria, Philippines, Republic of Moldova, Timor-Leste, Uganda, Viet Nam and Zimbabwe), 5 other countries had started, and 14 were planning to implement a survey in 2019 (map).

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4. Methods to estimate disease burden

Methods used by WHO to translate surveillance and survey data into estimates of TB incidence and mortality need to be periodically reviewed. The latest methods are documented in WHO’s Global Tuberculosis Report.

The first milestones of the End TB Strategy, set for 2020, are a 35% reduction in the absolute number of TB deaths and a 20% reduction in the TB incidence rate, compared with levels in 2015. To reach these milestones, the TB incidence rate needs to be falling by 4–5% per year globally by 2020 and the proportion of people with TB who die from the disease (the case fatality ratio or CFR) needs to be reduced to 10% globally by 2020.

Globally, the absolute number of TB deaths (excluding TB deaths among HIV-positive people) and the TB incidence rate have fallen since 2000. The number of HIV-negative TB deaths fell from 1.8 million in 2000 to 1.3 million in 2017. However, the global rate of decline in the TB incidence rate from 2016-2017 was only 2% per year, and the case fatality ratio in 2017 was 16%.

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5. Analysis and use of data

Understanding and using tuberculosis data provides practical advice on analysis of TB-relevant data, especially surveillance data from national notification and vital registration systems, and data from periodic surveys.

A comprehensive country package is now available to support the transition from paper to digital TB surveillance and the routine analysis and use of data for action. The package includesDHIS2 TB modules for aggregated TB data and case-based TB data and a curriculum with accompanying exercises on data interpretation, based on the standard analytical dashboards that are part of the DHIS2 modules.

The TB country package is being developed alongside packages for other programmes (e.g. HIV, immunization, hepatitis, maternal, Reproductive, Maternal, Newborn, Child and Adolescent Health (RMNCAH)) under the umbrella of the Health Data Collaborative.

A guide on TB modelling at country level was published in 2018. It was developed under the leadership of the TB Modelling and Analysis Consortium (TB MAC), in close collaboration with WHO.

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