Studies on effects of e-cigarettes on smoking cessation unreliable
More studies of good quality are needed to determine the impacts of electronic nicotine delivery systems or electronic non-nicotine delivery systems on cessation of smoking, a new meta-analysis recommends. The current existing literature is not of high enough quality or certainty to yield meaningful conclusions.
Studies published in the Cochrane Central Register of Controlled Trials, Embase, Medline, Cinahl, PsychInfo and Web of Science were screened for randomized controlled trials and prospective cohort studies that investigated electronic nicotine or non-nicotine delivery systems.
Those that had a sample of smokers, compared the interventions to no cessation aids and alternative cessation aids were included. Outcomes of the studies were smoking cessation, at least 50 percent reduction in cigarette use and adverse events.
After applying the inclusion and exclusion criteria, only three randomized controlled trials corresponding to 1,007 individuals, and 9 prospective cohort studies corresponding to 13,115 individuals were found to be eligible for analysis.
Analysis of two randomized controlled trials showed that using electronic nicotine delivery systems may result in greater smoking cessation compared to electronic non-nicotine delivery systems (risk ratio [RR], 2.03; 95 percent CI, 0.94 to 4.38; p=0.07).
On the other hand, analysis of eight cohort studies reported no significant improvements in smoking cessation when electronic nicotine delivery systems were employed compared to no such system (odds ratio [OR], 0.74; 0.55 to 1.00; p=0.051).
In the analysis of both types of studies, confidence in the evidence was rated as low because of risk of bias and imprecise data, both of which were attributed to lack of blinding, missing outcome data and imprecision in assessment.
Sensitivity analyses in both randomized controlled trials and cohort studies showed inconsistencies with the findings from the primary synthesised analyses.
The results of the meta-analysis thus show that existing literature on using either electronic nicotine or non-nicotine delivery systems for smoking cessation is insufficient and of not high enough quality to draw any meaningful conclusions.