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

INTRODUCTION: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: The present meta-analysis suggests that smoking by family members and friends is significantly associated with increased probability of e-cigarette use in adolescents.