Methods Used by WHO to Estimate the Global Burden of TB Disease

This paper describes methodological details used by WHO in 2016 to estimate TB incidence, prevalence and mortality. Incidence and mortality are disaggregated by HIV status, age and sex. Methods to derive MDR-TB burden indicators are detailed. Four main methods were used to derive incidence: (i) case notification data combined with expert opinion about case detection gaps (74 countries representing 22% of global incidence in 2015); (ii) results from TB prevalence surveys (20 countries, 62% of global incidence); (iii) notifications in high-income countries adjusted by a standard factor to account for under-reporting and underdiagnosis (118 countries, 15.5% of global incidence) and (iv) capture-recapture modelling (5 countries, 0.5% of global incidence). Mortality was obtained from national vital registration systems of mortality surveys in 128 countries (52% of global HIV-negative TB mortality). In other countries, mortality was derived indirectly from incidence and case fatality ratio.