INTRODUCTION: Several published systematic reviews have examined the potential associations between e-cigarette use and cigarette smoking, but their methodological and/or reporting quality have not yet been assessed. This systematic quality review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and AMSTAR (A MeaSurement Tool to Assess systematic Reviews) 2 to evaluate the quality of systematic reviews investigating potential associations between e-cigarette use and cigarette smoking.

MATERIALS AND METHODS: PubMed/MEDLINE, Embase, and PsycINFO were searched from 01 January 2007 to 24 June 2020. Methodological quality was assessed using AMSTAR 2, and reporting quality was assessed using PRISMA guidelines.

RESULTS: Of 331 potentially relevant systematic reviews, 20 met predefined inclusion criteria. Most reviews (n = 15; 75%) reported on e-cigarette use and cigarette smoking cessation, while three reported on e-cigarette use and cigarette smoking initiation (15%); and two reported on cigarette smoking initiation and cessation (10%). According to AMSTAR 2 guidelines, 18 of the 20 reviews (90%) were "critically low" in overall confidence of the results, while two were ranked "low." Additionally, reporting quality varied across the reviews, with only 60% reporting at least half of the PRISMA items.

DISCUSSION: Methodological limitations were identified across reviews examining potential associations between e-cigarette use and cigarette smoking behaviors, indicating that findings from these reviews should be interpreted with caution.

CONCLUSIONS: Future systematic reviews in this field should strive to adhere to AMSTAR 2 and PRISMA guidelines, to provide high quality syntheses of the available data with transparent and complete reporting.