Lifetime burden of disease due to incident tuberculosis: a global reappraisal including post-tuberculosis sequelae

Abstract

Background: Many individuals who survive tuberculosis disease face ongoing disability and elevated mortality risks. However, the impact of post-tuberculosis sequelae is generally omitted from policy analyses and disease burden estimates. We therefore estimated the global burden of tuberculosis, inclusive of post-tuberculosis morbidity and mortality.

Methods: We constructed a hypothetical cohort of individuals developing tuberculosis in 2019, including pulmonary and extrapulmonary disease. We simulated lifetime health outcomes for this cohort, stratified by country, age, sex, HIV status, and treatment status. We used disability-adjusted life-years (DALYs) to summarise fatal and non-fatal health losses attributable to tuberculosis, during the disease episode and afterwards. We estimated post-tuberculosis mortality and morbidity based on the decreased lung function caused by pulmonary tuberculosis disease.

Findings: Globally, we estimated 122 (95% uncertainty interval [UI] 98-151) million DALYs due to incident tuberculosis disease in 2019, with 58 (38-83) million DALYs attributed to post-tuberculosis sequelae, representing 47% (95% UI 37-57) of the total burden estimate. The increase in burden from post-tuberculosis varied substantially across countries and regions, driven largely by differences in estimated case fatality for the disease episode. We estimated 12·1 DALYs (95% UI 10·0-14·9) per incident tuberculosis case, of which 6·3 DALYs (5·6-7·0) were from the disease episode and 5·8 DALYs (3·8-8·3) were from post-tuberculosis. Per-case post-tuberculosis burden estimates were greater for younger individuals, and in countries with high incidence rates. The burden of post-tuberculosis was spread over the remaining lifetime of tuberculosis survivors, with almost a third of total DALYs (28%, 95% UI 23-34) accruing 15 or more years after incident tuberculosis.

Interpretation: Post-tuberculosis sequelae add substantially to the overall disease burden caused by tuberculosis. This hitherto unquantified burden has been omitted from most previous policy analyses. Future policy analyses and burden estimates should take better account of post-tuberculosis, to avoid the potential misallocation of funding, political attention, and research effort resulting from continued neglect of this issue.

Funding: National Institutes of Health.

Figure 1

Estimates of YLLs (A), YLDs (B), and DALYs (C) attributable to tuberculosis disease in 2019, stratified by age group of disease incidence, and disease period* YLL=years of life lost. YLD=years lived with disability. DALYs=disability-adjusted life-years. *Black bars represent 95% uncertainty intervals.

Figure 2

Average DALYs per incident tuberculosis case from increased disability and mortality rates attributable to tuberculosis, stratified by tuberculosis disease and post-tuberculosis period* Area of each green and blue rectangle is proportional to the number of DALYs indicated, other dimensions not to scale. Values in parentheses represent 95% uncertainty intervals. DALYs=disability-adjusted life-years. *Total DALYs per incident tuberculosis case are equal to the sum of these values.

Figure 3

DALYs per incident tuberculosis case, stratified by tuberculosis disease and post-tuberculosis period* YLL=years of life lost. YLD=years lived with disability. DALYs=disability-adjusted life-years. *Total DALYs per incident tuberculosis case equal to the sum of these values. Values in parentheses represent 95% uncertainty intervals.