Association of electronic cigarette vaping and subsequent smoking relapse among former smokers

Background: Former combustible cigarette smokers who vape e-cigarettes after quitting smoking may experience health benefits if post-quit vaping prevents smoking relapse. Methods: Former combustible cigarette smokers aged > 18 that were recent (quit <= 12 months) or long-term (quit > 12 months) quitters at baseline were re-surveyed at 1-year follow-up in the Population Assessment of Tobacco and Health (PATH) U.S. nationally-representative longitudinal study. Associations of baseline e-cigarette vaping status (never use, prior use, current occasional use, and current regular use) and smoking relapse (vs. abstinence) at follow-up were estimated. Results: Among recent quitters (N = 884), the prevalence of follow-up smoking relapse was 31.6%, 39.0%, 51.6%, and 31.9% among never (N = 233), prior (N = 399), current occasional (N = 56), and current regular (N = 196) baseline e-cigarette users, respectively. Baseline e-cigarette use was not associated with smoking relapse at follow-up after covariate adjustment. In long-term quitters (n = 3210), follow-up smoking relapse was 1.8%, 10.4%, 9.6%, and 15.0% among never (N = 2479), prior (N = 588), current occasional (N = 45), and current regular (N = 98) baseline e-cigarette users, respectively. Both prior use (AOR = 2.00, CI [1.25-3.20]) and current regular use of e-cigarettes (AOR = 3.77, CI [1.48-9.65]) had higher odds of subsequent smoking relapse as compared to never e-cigarette users after covariate adjustment. Among relapsers, baseline e-cigarette vaping was not associated with smoking frequency or intensity at follow-up. Conclusions: Vaping more than one year after quitting smoking was associated with smoking relapse at 12-month follow-up in a nationally-representative sample. Further studies are needed to evaluate whether this association is causal.