Key messages
- Nicotine e-cigarettes can help individuals stop smoking for at least six months. Evidence shows they work better than nicotine replacement therapy and probably better than e-cigarettes without nicotine.
- They may work better than no support or behavioural support alone.
- However, more evidence is required, especially about newer types of e‐cigarettes that have better nicotine delivery, as better nicotine delivery might help more individuals quit smoking.
Background Electronic cigarettes (e-cigarettes) are handheld electronic vaping devices that heat a liquid, usually containing nicotine and flavourings. Using an e-cigarette is commonly known as ‘vaping’. E-cigarettes allow users to inhale nicotine in a vapour rather than smoke. Because they do not burn tobacco, e-cigarettes do not expose users to the same levels of chemicals that can cause diseases as conventional cigarettes. Many individuals use e-cigarettes to help them stop smoking tobacco.
Objective The objective of this Cochrane Review was to examine the safety, tolerability, and effectiveness of using e-cigarettes to help individuals who smoke tobacco achieve long‐term smoking abstinence, in comparison to non‐nicotine e-cigarettes, other smoking cessation treatments, and no treatment. This review update is part of a living systematic review.
Selection criteria The researchers included trials in which participants who smoke were randomized to an e-cigarette or control group. Uncontrolled intervention studies in which all participants received an e-cigarette intervention were also included, as these studies have the potential to provide further information on harms and longer‐term use. Studies had to report an eligible outcome.
Data collection Standard Cochrane methods for screening and data extraction were followed. Critical outcomes were abstinence from smoking after at least six months, adverse events (AEs), and serious adverse events (SAEs).
Main results A total of 88 studies, representing 27,235 participants, of which 47 were randomized controlled trials (RCTs), were included. Of the included studies, ten were rated at low risk of bias, 58 at high risk, and the remainder at unclear risk.
There was high-certainty evidence nicotine e-cigarettes increase quit rates compared to nicotine replacement therapy (NRT), which might translate to an additional four quitters per 100. There was moderate-certainty evidence the rate of occurrence of AEs was similar between groups. SAEs were rare, and there was insufficient evidence to determine whether rates differed between groups.
There was moderate‐certainty evidence nicotine e-cigarettes increase quit rates compared to non‐nicotine e-cigarettes. This might lead to an additional three quitters per 100. There was moderate‐certainty evidence of no difference in the rate of AEs between these groups. There was insufficient evidence to determine whether rates of SAEs differ between groups.
Due to the risk of bias, there was low‐certainty evidence that quit rates may be higher for participants randomized to nicotine e-cigarettes compared to behavioural support only/no support. This may represent an additional four quitters per 100. There was some evidence that non‐serious AEs may be more common in people randomized to nicotine e-cigarettes and, again, insufficient evidence to determine whether rates of SAEs differed between groups.
Data from non‐randomized studies were consistent with RCT data. The most commonly reported AEs were throat/mouth irritation, headache, cough, and nausea, which tended to dissipate with continued e-cigarette use.
Conclusions There is high‐certainty evidence electronic cigarettes with nicotine increase quit rates compared to NRT and moderate‐certainty evidence that they increase quit rates compared to e-cigarettes without nicotine. Evidence comparing nicotine e-cigarettes with usual care/no treatment also suggests benefits but is less certain due to the risk of bias in the study design. Overall, SAE incidence was low across all study arms. Evidence of serious harm from nicotine e-cigarettes was not detected, but the longest follow‐up was two years, and the number of studies was small. More research is required, and further RCTs are underway.This living systematic review will be updated when new evidence becomes available.
