WHO convenes global experts to update guidance on national TB prevalence surveys

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13 October 2022 Departmental news WHO Geneva

A meeting of a subgroup of WHO’s Global Task Force on TB Impact Measurement was held in Geneva on 28–29 September to review draft content that has been developed for the new guidance on national TB prevalence surveys. The meeting brought together global experts in the design, implementation, analysis and/or reporting of national TB prevalence surveys, including people from national TB programmes, universities, national institutes and technical agencies, as well as independent consultants. Content related to screening and diagnostic algorithms, case definitions, diagnostic investigations, documents and data management, chest radiography and clinical management was discussed. Planned next steps include the update and finalization of the document with the targeted publication date in mid-2023.

“The COVID-19 pandemic has generated substantial uncertainty about the level of and trends in TB disease burden in many countries, notably those in which there have been major disruptions to TB case detection” said Dr Tereza Kasaeva, Director of WHO’s Global TB Programme. “It is possible that the burden of TB has increased, but this cannot be ascertained from available surveillance data. We urgently need to reinvigorate national and global commitments to national TB prevalence surveys to produce new, robust and nationally-representative data. The new guidance document will support countries in enabling this.”

Strong surveillance systems that produce reliable and high-quality data are the best way to reliably track the level of and trends in TB disease burden, and the impact of programmatic interventions. Some countries already have such systems, allowing TB incidence to be monitored using national TB notification data and TB mortality to be monitored using data on causes of death from national vital registration (VR) systems. However, in many countries with a high burden of TB, periodic studies are still required to provide complementary data. These include population-based national surveys of the prevalence of TB disease (national TB prevalence surveys).

Since 2007, national TB prevalence surveys have been among the strategic areas of work of the Global Task Force on TB Impact Measurement (convened by the Global TB Programme’s TB monitoring, evaluation and strategic information unit). The Task Force brings together national TB programmes, global experts in TB epidemiology, statistics and modelling, independent consultants and representatives from partner agencies. Between 2007 and 2021, 35 national surveys were completed in 31 countries; almost all used the methods recommended in current WHO guidance, commonly referred to as the “Lime book”.

A new edition of the WHO guidance on national TB prevalence surveys is now required, to reflect all of the experience and lessons learned from surveys implemented in the past 15 years (for example, see National TB prevalence surveys: 2007-2016) as well as new developments since the lime book was published in 2011 – notably, widespread use of Xpert assays and much more use of digital technologies, both for chest X-rays and data management.

About the WHO Global Task Force on TB Impact Measurement

The WHO Global Task Force on TB Impact Measurement was established in 2006. It is convened by the Global TB Programme’s TB monitoring, evaluation and strategic information unit. In the context of WHO’s End TB Strategy and the Sustainable Development Goals (SDGs), the Task Force’s mission is to:

1. Ensure rigorous, robust and consensus-based assessments of progress towards milestones and targets set in the SDGs and WHO End TB Strategy, at global, regional and country levels; and

2. Guide, promote and support the analysis and use of TB surveillance and survey data for policy, planning and programmatic action.

The Task Force has four major strategic areas of work:

1. Strengthening surveillance – this includes national systems for TB surveillance (for direct measurement of TB incidence) and national VR systems (for direct measurement of the number of deaths caused by TB);

2. Priority studies to periodically measure TB disease burden – these include (but are not limited to) national TB prevalence surveys, drug resistance surveys and surveys of costs faced by TB patients and their households;

3. Periodic review of methods used by WHO to produce estimates of the burden of TB disease; and

4. Analysis and use of TB surveillance and survey data at country level.

More information on the Task Force is available in the online brochure.