Secondhand smoke exposure and current tobacco and/or nicotine use among adolescents in Kenya and Nigeria: a survey-weighted inverse probability weighting analysis

Abstract

Abstract Introduction Secondhand smoke (SHS) exposure is associated with adolescent tobacco and nicotine use but nationally representative evidence from sub-Saharan Africa is limited. We examined this association among adolescents in Kenya and Nigeria using survey-weighted inverse probability weighting. Methods We analysed cross-sectional data from the 2024 Data on Youth Tobacco in Africa household survey of adolescents aged 10–17 years in Kenya (n=6435) and Nigeria (n=7502). SHS exposure was self-reported. Current use of any tobacco and/or nicotine product was self-reported past-30-day use of cigarettes, roll-your-own tobacco, shisha, smokeless tobacco, heated tobacco products, e-cigarettes or nicotine pouches. We estimated the average treatment effect (ATE) and average treatment effect on the treated (ATT), adjusting for age, sex, residence, school attendance, adolescent employment, household head education, household size, wealth and country in pooled analyses. We assessed effect modification by country and conducted regression, location-specific and E-value sensitivity analyses. Results Overall, 38.2% reported SHS exposure and 3.1% reported current use; 72.1% of current users were boys. Current use was more common among SHS-exposed than unexposed adolescents (4.4% vs 2.4%). In pooled analyses, SHS exposure was associated with a 2.65 percentage-point higher probability of current use (ATE: +2.65 pp; 95% CI 1.46 to 3.83); the ATT was 2.42 percentage points (95% CI 1.35 to 3.49). The ATE was larger in Nigeria (+3.94 pp; 95% CI 1.95 to 5.93) than Kenya (+1.32 pp; 95% CI 0.19 to 2.45), with evidence of effect modification (interaction p=0.019). Sensitivity analyses were consistent, although unmeasured confounding remains possible. Conclusions SHS exposure was associated with a higher probability of adolescent tobacco and/or nicotine use. Because exposure and outcome were measured cross-sectionally, temporality and causality cannot be established. Strengthening smoke-free policies may help reduce adolescent SHS exposure and tobacco and/or nicotine use.