Effectiveness of nicotine vape products (E-cigarettes) as a smoking cessation aid for US adults: a narrative review of findings from the population assessment of tobacco and health study.

INTRODUCTION: Controversy remains regarding whether nicotine vaping products (NVPs) are associated with cigarette cessation in observational research. Reviews have largely overlooked studies using the same data source. To address this gap, we conducted a narrative review to examine the heterogeneity in the reported association that used data from the same source, which may help to explain inconsistent findings. METHODS: We identified empirical studies through PubMed and Google searches that exclusively used the Population Assessment of Tobacco and Health (PATH) Study data to examine associations between NVP use and smoking cessation among adults. Adapting Arksey and O'Malley's approach, we extracted and summarized key study characteristics, including inclusion criteria, participant characteristics, study durations, definitions of NPV exposure and smoking outcomes, covariate adjustment, and analytic methods. We also conducted regression and regression tree analyses to examine how these characteristics were related to study findings. RESULTS: We identified 28 articles comprising 38 analyses of NVP use and cigarette cessation. Of these, 24 studies (63.2%) reported a positive association, concluding that NVP use predicted cessation. Substantial heterogeneity existed across study characteristics. Evidence suggests that daily NVP use may promote cessation, whereas studies restricted to participants with an intention to quit were less likely to observe cessation than those including participants regardless of quit intention. CONCLUSIONS: Researchers are advised against making broad claims based on any single PATH Study analysis of NVP use and smoking cessation. Rather, multiple studies using the same data source must be carefully examined in order to synthesize evidence and assess consistency of the findings. IMPLICATIONS: Whether NVPs help adult smokers quit remains controversial in observational research, partly due to heterogeneity in study characteristics across studies using the same data source. Our review of observational studies based exclusively on a single data source-an approach often overlooked-suggests that (1) daily NVP use may support smoking cessation, and (2) studies that restricted participants to those with an intention to quit were less likely to observe cessation than studies that included participants regardless of quit intention. These findings underscore the value of multiple analyses using the same data source to synthesize evidence and assess consistency.