Does Electronic Cigarette Use Predict Abstinence from Conventional Cigarettes among Smokers in Hong Kong?

Objectives: To investigate the effects of ever use of electronic cigarettes (ECs), many of which lack nicotine, on abstinence from convention cigarettes among Hong Kong adult smokers. Methods: We collected data from 956 daily smokers in 2014-2015 regarding ever EC use and smoking behaviors at baseline, any and past 30-day EC use at the 3-month follow-up. Outcomes measured at 6 months included past 7-day point prevalence abstinence (PPA), biochemically validated quitting, smoking reduction (>= 50% from baseline) and cessation attempt. Logistic regression yielded adjusted odds ratios (AOR) for quitting in relation to EC use, adjusting for socio-demographic characteristics and smoking profile. Complete case, missing observation as smoking and propensity score analyses were conducted. Results: By complete case, ever EC use at baseline did not predict self-reported PPA (AOR 0.99, 95% CI 0.57-1.73), biochemically validated quitting (AOR 1.22, 95% CI 0.64-2.34), cessation attempt (AOR 0.74, 95% CI 0.48-1.14), or smoking reduction (AOR 0.89, 95% CI 0.54-1.47). EC use during the first 3 months did not predict quitting (AOR 1.02, 95% CI 0.22-4.71). Similar results were observed for missing observations as smoking and propensity score analyses. Conclusions: Any use of ECs, many of which lack nicotine, did not predict smoking abstinence among Hong Kong adult smokers.