Table 1.
Characteristics of the included systematic reviews and randomized controlled trials
| Study and Year | Location | Population/intervention | Comparison | Outcomes | Included study types |
|---|---|---|---|---|---|
| Kalkhoran et al.26 (2016) | USA | Adult smokers with nicotine EC use | Non-EC users | Probability of smoking cessation | 15 cohort studies, 3 cross-sectional studies and 2 clinical trials |
| El Dib et al.27 (2017) | Brazil | Adult smokers with nicotine EC use | Placebo EC | Probability of smoking cessation | 3 RCTs and 9 prospective cohort studies |
| Hartmann-Boyce et al.28 (2016) | UK | Adult smokers with nicotine EC use | Placebo EC | Probability of smoking cessation | 3 RCTs and 21 cohort studies |
| Khoudigian et al.29 (2016) | Canada | Adult smokers with nicotine EC use | Placebo EC | Probability of smoking cessation | 3 RCTs and 2 comparative observational studies |
| Rahman et al.30 (2015) | Australia | Adult smokers with nicotine EC use | Placebo EC | Probability of smoking cessation | 2 RCTs, 2 cohort studies and 2 cross-sectional studies |
| Soneji et al.31 (2017) | Lebanon | Non-smoking teenagers with current or past 30-day nicotine EC use | Never or non-past 30-day EC users | Probability of cigarette smoking initiation | 9 cohort studies |
| Hajek et al.32 (2019) | UK | Nicotine EC users (n=438) | NRT (n=446) | 1-year abstinence rate | RCT |
| Tseng et al.33 (2016) | USA | 4.5% nicotine EC users (n=50) | Placebo EC (n=49) | Abstinence rate at week 3 | RCT |
| Lee et al.34 (2019) | Korea | Nicotine EC users (n=75) | Nicotine gum (n=75) | Abstinence rate at 9–24 weeks | RCT |
| Li et al.35 (2019) | UK | Nicotine EC users (n=439) | NRT (n=447) | 1-year abstinence rate | RCT |
| Halpern et al.36 (2018) | USA | Nicotine EC users (n=1199) | No treatment (n=813) | 6-month abstinence rate | RCT |
EC: electronic cigarette. NRT: nicotine replacement therapy.