TB morbidity estimates overlook the contribution of post-TB disability: evidence from urban Malawi

Abstract

IntroductionDespite growing evidence of the long-term impact of tuberculosis (TB) on quality of life, Global Burden of Disease (GBD) estimates of TB-related disability-adjusted life years (DALYs) do not include post-TB morbidity, and evaluations of TB interventions typically assume treated patients return to pre-TB health. Using primary data, we estimate years of life lost due to disability (YLDs), years of life lost due to premature mortality (YLL) and DALYs associated with post-TB cardiorespiratory morbidity in a low-income country.MethodsAdults aged ≥15 years who had successfully completed treatment for drug-sensitive pulmonary TB in Blantyre, Malawi (February 2016–April 2017) were followed-up for 3 years with 6-monthly and 12-monthly study visits. In this secondary analysis, St George’s Respiratory Questionnaire data were used to match patients to GBD cardiorespiratory health states and corresponding disability weights (DWs) at each visit. YLDs were calculated for the study period and estimated for remaining lifespan using Malawian life table life expectancies. YLL were estimated using study mortality data and aspirational life expectancies, and post-TB DALYs derived. Data were disaggregated by HIV status and gender.ResultsAt treatment completion, 222/403 (55.1%) participants met criteria for a cardiorespiratory DW, decreasing to 15.6% after 3 years, at which point two-thirds of the disability burden was experienced by women. Over 90% of projected lifetime-YLD were concentrated within the most severely affected 20% of survivors. Mean DWs in the 3 years post-treatment were 0.041 (HIV-) and 0.025 (HIV+), and beyond 3 years estimated as 0.025 (HIV-) and 0.010 (HIV+), compared with GBD DWs of 0.408 (HIV+) and 0.333 (HIV-) during active disease. Our results imply that the majority of TB-related morbidity occurs post-treatment.ConclusionTB-related DALYs are greatly underestimated by overlooking post-TB disability. The total disability burden of TB is likely undervalued by both GBD estimates and economic evaluations of interventions, particularly those aimed at early diagnosis and prevention.

Addressing the burden of HIV-associated chronic lung disease in West Africa

“…This is clearly of relevance to the majority global HIV population who bear the additional burden of endemic TB. The findings reflect recent work from Malawi describing how long-term negative sequelae of pulmonary TB both on airways obstruction [reduced forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC)] and bronchiectasis, and their corresponding symptoms, are common at the end of TB treatment and although reducing over time, persist indefinitely in a significant minority, particularly those also living with HIV [14,15].…”

“…A question which the authors did not directly investigate, is the effect on health-related quality of life (HQoL) from CLD in their population. OLD has been associated with lower HQoL elsewhere in PWH [18], as has OLD secondary to TB [15] and may be predicted to progress with age [19]. This will be important to quantify using universal/generalizable measures such as the EQ-5D-5L both to understand the impact of CLD relative to Here the authors correctly highlight the greater importance of addressing TB risk over smoking cessation, arguably the priority intervention in HICs.…”

Disease burden of tuberculosis and post-tuberculosis in Inner Mongolia, China, 2016–2018 — based on the disease burden of post-TB caused by COPD

“…In addition to respiratory symptoms, there was an increased morbidity and mortality of cardiovascular disease in post-patients with TB [ 54 ]. These studies suggested that, among those who have been cure of TB, except for COPD, other respiratory diseases, cardiovascular diseases, and neurological damage were also related to the disease burden of post-TB [ 55 ]. Therefore, when other systemic diseases caused by post-TB were considered, the burden of post-TB in Inner Mongolia might be significantly heavier than our results.…”

Post-TB health and wellbeing

“… 64 Recent evidence from Blantyre, Malawi, demonstrated that over 90% of projected lifetime YLD was concentrated within the most severely affected 20% of survivors. 65 Per-case post-TB burden estimates are greater among women, younger people, HIV-positive individuals and those from countries with high-incidence rates. 65 , 72 A model of some of the psychological and socioeconomic consequences that contribute to poor HRQoL, examples of tools used to measure these and how PTLD contributes to the burden of TB disease is shown in Figure 4 .…”