E-cigarettes and nicotine abstinence: a meta-analysis of randomised controlled trials

Eur Respir Rev. 2022 Mar 23;31(163):210215. doi: 10.1183/16000617.0215-2021. Print 2022 Mar 31.


Objectives: To determine the effects of electronic cigarettes (e-cigarettes) as a therapeutic intervention compared to nicotine replacement therapy (NRT) on nicotine abstinence.

Methods: Two authors independently searched the PubMed, Embase, PsycInfo and Cochrane Central Register of Controlled Trials databases for articles published up to and including 10 July 2021. We included randomised controlled trials (RCTs) in which nicotine e-cigarettes were compared to NRT among current cigarette users. The primary outcome was abstaining from all nicotine-delivery devices. Secondary outcomes were 1) allocated product use (e-cigarettes or NRT) among successful cigarette quitters and 2) quitting cigarettes at the end of the trial using fixed-effect Mantel-Haenszel models.

Results: We included four RCTs representing 1598 adult participants (51.0% females). The mean age of participants in these studies ranged from 41 to 54 years, while average baseline smoking ranged from 14 to 21 cigarettes per day. Compared to NRT, e-cigarette use was associated with lower nicotine abstinence rates at the longest follow-up (risk ratio 0.50 (95% CI 0.32-0.77)). Among successful cigarette quitters, the risk of allocated product use by the end of the observational time was higher for e-cigarette users compared to NRT (risk ratio 8.94 (95% CI 3.98-20.07)). E-cigarette users had higher cigarette smoking cessation rates compared to NRT users (risk ratio 1.58 (95% CI 1.20-2.08)).

Conclusions: The use of e-cigarettes as a therapeutic intervention for smoking cessation may lead to permanent nicotine dependence.

Publication types

  • Meta-Analysis

MeSH terms

  • Adult
  • Electronic Nicotine Delivery Systems*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Nicotine / adverse effects
  • Randomized Controlled Trials as Topic
  • Smoking Cessation*
  • Tobacco Use Cessation Devices / adverse effects
  • Vaping* / adverse effects


  • Nicotine