Smoking by family members and friends and electronic-cigarette use in adolescence: A systematic review and meta-analysis

Evidence suggests that smoking by family members and friends is a strong predictor of smoking uptake in adolescents, yet the influence on electronic cigarette (e-cigarette) use has not been systematically reviewed and quantified. Relevant studies were identified by searches of the PubMed and ScienceDirect databases up to December 2016. The summary odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a random-effects model. A total of 21 studies were included in this meta-analysis. A positive association was observed between adolescent e-cigarette use and smoking by family members (OR=1.47, 95% CI=1.30-1.66) and friends (OR=2.72, 95% CI=1.87-3.95), even after adjusting for the individual smoking status. Stratified by family members, the association with smoking in siblings (OR=1.87, 95% CI=1.35-2.60) was more prominent than that in parents (OR=1.41, 95% CI=1.191-.68) and other family members (OR=1.39, 95% CI=1.12-1.72). The present meta-analysis suggests that smoking by family members and friends is significantly associated with increased probability of e-cigarette use in adolescents.