Methods used by WHO to estimate the global burden of TB disease

This paper describes methodological details used by WHO in 2021 to estimate TB incidence and mortality for the period 2000-2020. Incidence and mortality are disaggregated by HIV status, age and sex. Four main methods are used to derive incidence over the period 2000-2019: (i) results from TB prevalence surveys; (ii) notifications in high-income countries adjusted by a standard factor to account for under-reporting and underdiagnosis and (iii) national inventory studies; (iv) case notification data combined with expert opinion about case detection gaps. Mortality is obtained from national vital registration systems of mortality surveys. In other countries, mortality is derived indirectly from incidence and case fatality ratio. For the year 2020, TB incidence and mortality are estimated using new dynamic and statistical models in 16 and 111 countries, respectively. These new methods were required to produce estimates that account for the major disruptions to the provision of and access to TB diagnostic and treatment services that have occurred in the context of the COVID-19 pandemic.