Temporal imprecision and unaddressed confounding limit inferences whether e-cigarette vaping provides real-world benefits or harms for combustible cigarette smoking cessation. This naturalistic, multilevel longitudinal study of US adults examined whether (semi-)monthly transitions in e-cigarette vaping were associated with attaining smoking abstinence and subsequent post-quit relapse. A nationally representative panel of 1255 adults who smoked at baseline completed up to 22 biweekly and 13 monthly surveys between May 2020 and May 2022. Using multilevel longitudinal models, we assessed within-person transitions in past 7-day vaping status (none, non-daily, daily) as time-lagged, time-varying predictors of 7-day point-prevalence smoking outcomes (0 vs 1-7 days). Results showed that daily vaping was associated with higher odds of achieving smoking abstinence 2 weeks later (30.4% vs 16.3%; adjusted-RR, 2.27; 95% CI, 1.41-3.69), while non-daily vaping was not significantly associated (22.5% vs 16.3%; adjusted-RR, 1.05; 95% CI, 0.85-1.37). In 557 instances where participants had achieved at least 1 month of smoking abstinence, both daily (adjusted-HR, 1.31; 95% CI, 1.09-1.70) and non-daily (adjusted-HR, 2.82; 95% CI, 2.07-4.61) vaping were linked to increased relapse risk compared to no vaping. These findings suggest that while daily vaping may support short-term smoking cessation, it is associated with a heightened risk of relapse among individuals who have already quit.
Keywords: electronic cigarettes; multilevel longitudinal analysis; smoking cessation; smoking relapse.
© The Author(s) 2025. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health.