Underweight increases the risk of early death in tuberculosis patients.

Evidence regarding the association between BMI and mortality in tuberculosis (TB) patients is limited and inconsistent. We investigated the impact of BMI on TB-specific and non-TB-specific mortality with respect to different timing of death. All Taiwanese adults with TB in Taipei were included in a retrospective cohort study in 2012-2014. Multinomial Cox proportional hazards regression was used to evaluate the associations between BMI, cause-specific mortality and timing of death. Of 2410 eligible patients, 86·0 % (2061) were successfully treated, and TB-specific and non-TB-specific mortality occurred for 2·2 % (54) and 13·9 % (335), respectively. After controlling for potential confounders, underweight was significantly associated with a higher risk of all-cause mortality (adjusted hazard ratio (AHR) 1·57; 95 % CI 1·26, 1·95), whereas overweight was not. When cause-specific death was considered, underweight was associated with an increased risk of either TB-specific (AHR 1·85; 95 % CI 1·03, 3·33) or non-TB-specific death (AHR 1·52; 95 % CI 1·19, 1·95) during treatment. With joint consideration of cause-specific and timing of death, underweight only significantly increased the risk of TB-specific (AHR 2·23; 95 % CI 1·09, 4·59) and non-TB-specific mortality (AHR 1·81; 95 % CI 1·29, 2·55) within the first 8 weeks of treatment. This study suggests that underweight increases the risk of early death in TB patients during treatment.