Childhood tuberculosis and exposure to indoor air pollution: a systematic review and meta-analysis

BACKGROUND: Indoor air pollution (IAP) from environmental tobacco smoke (ETS) and biomass fuel smoke (BMS) poses respiratory health risks, with children and women bearing the major burden. OBJECTIVES: We used a systematic review and meta-analysis to investigate the relation between childhood tuberculosis (TB) and exposure to ETS and BMS. METHODS: We searched three databases for epidemiological studies that investigated the association of childhood TB with exposure to ETS and BMS. We calculated pooled estimates and heterogeneity for studies eligible for inclusion in the meta-analysis and stratified studies on ETS by outcome. RESULTS: Five case-control and three cross-sectional studies were eligible for inclusion in the meta-analysis and quality assessment. Pooled effect estimates showed that exposure to ETS is associated with tuberculous infection and TB disease (OR 1.9, 95%CI 1.4-2.9) among exposed compared to non-exposed children. TB disease in ETS studies produced a pooled OR of 2.8 (95%CI 0.9-4.8), which was higher than the OR for tuberculous infection (OR 1.9, 95%CI 0.9-2.9) for children exposed to ETS compared to non-exposed children. Studies on BMS exposure were too few and too small to permit a conclusion. CONCLUSION: Exposure to ETS increases the risk of childhood TB disease or tuberculous infection.