Early smoke signals mixed about e-cigarettes

June 2015 Vol 15 (3)

This edition’s critically appraised topic (CAT) looks at whether reaching for an e-cigarette has been proven to be more helpful to quitters than slapping on a nicotine patch.

CLINICAL BOTTOM LINE:

The limited studies to date show e-cigarettes (delivering low nicotine levels) are no more effective than nicotine patches at helping smokers to quit but may help smokers unable to quit to reduce their cigarette consumption. Also, short term e-cigarette use was not associated with serious adverse effects. More studies are needed about the safety and effectiveness of e-cigarettes as a smoking cessation aid and these studies are underway. 

CLINICAL SCENARIO:

As a nurse, you frequently ask patients about their tobacco use. Some people swear that electronic cigarettes (e-cigarettes) helped them quit, saying that nicotine patches didn’t help at all. E-cigarettes are increasingly used as a smoking cessation aid, despite some concern about their toxicity. You decide to review the evidence to find out how effective and safe e-cigarettes really are.

QUESTION:

In comparison with nicotine patches, how effective and safe are e-cigarettes for helping tobacco smokers to quit?

SEARCH STRATEGY:

PubMed-Clinical queries (Therapy/Narrow):

electronic cigarettes AND nicotine

CITATION:

McRobbie, H., Bullen, C., Hartmann-Boyce, J., & Hajek, P. (2014). Electronic cigarettes for smoking cessation and reduction. Cochrane Database Syst Rev, 12, Cd010216. doi: 10.1002/14651858.CD010216.pub2. 

STUDY SUMMARY:

A systematic review assessing whether e-cigarettes could help smokers to stop smoking or cut down on their smoking and whether e-cigarettes are safe to use. Inclusion criteria were:

Type of study: randomised controlled trials (RCTs) involving current smokers who were motivated or unmotivated to quit. Randomised cross-over trials and cohort follow-up studies examining at least one week of e-cigarette use were also included to help assess adverse events.

Types of intervention: e-cigarettes compared with placebo (non-nicotine) e-cigarettes; e-cigarettes compared with alternative smoking cessation aids, including nicotine replacement therapy or no intervention; e-cigarettes added to standard smoking cessation treatment (behavioural or pharmacological or both) compared with standard treatment alone.

Outcomes: primary outcome was smoking cessation. Secondary outcomes were a reduction in cigarette use, and adverse events (serious and non-serious) after one week of use or longer. Smoking cessation and reduction follow-up was at least six from the start of the intervention.

STUDY VALIDITY:

A comprehensive search strategy was used to search six electronic databases (Cochrane Tobacco Addiction Group Specialised Register, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, PsycINFO, and CINAHL) from July 2004 to July 2014. Unpublished studies were sought via reference lists of located studies, the metaRegister of controlled trials database, and through contact with authors of relevant publications.

Two authors independently pre-screened the titles, abstracts and full-text versions of potentially relevant papers, assessed the risk of bias in each study, and undertook data extraction and data entry. Any disagreement was solved with a third reviewer. The risk of bias in each included study was assessed using the Cochrane Collaboration criteria. Assessment of publication bias was not feasible because of the small number of studies involved.

Overall, a high-quality review involving two high-quality RCTs and lower quality cohort studies

STUDY RESULTS:

A total of 594 articles were screened, of which 68 full-text articles were assessed for eligibility. From these, 29 articles representing 13 completed studies (2 RCTs and 11 cohort) and nine ongoing studies were located as suitable for inclusion in this review.

The two RCTs involved middle-aged, highly dependent smokers; the larger RCT (n= 657) was conducted in New Zealand and involved smokers motivated to quit. Just one study (the New Zealand study) compared nicotine e-cigarettes with nicotine patches. There was no difference between these two quit methods in smoking cessation rates at six months but people using nicotine-delivering e-cigarettes were significantly more likely to reduce their usual cigarette consumption by at least 50 per cent (Table).

Pooled data from two RCTs identified that users of nicotine e-cigarettes, compared with placebo
(no nicotine) e-cigarettes, were significantly more likely to stop smoking for at least six months. In those not able to quit, use of nicotine e-cigarettes reduced cigarette consumption by at least 50 per cent compared with use of placebo e-cigarettes (Table). Short-term use (up to two years) of e-cigarettes was not associated with serious adverse events.

COMMENTS:

Smoking abstinence was biochemically verified;smoking reduction was measured using self-report.

The e-cigarette interventions in this review delivered a lower level of nicotine than either the patches or latest generation of e-cigarettes. Higher levels of nicotine may help people to quit tobacco smoking by providing better withdrawal relief.

Because of their study design, cohort studies are at high risk of selection bias. As per protocol, authors focused on RCT data for analysing cessation and reduction outcomes.

Although the RCTs were of high quality, there were just two available and the results lacked precision. Because of this, the overall quality of the evidence is low.

Anecdotally, e-cigarettes are a popular quitting aid amongst smokers. Debate continues about the wisdom of New Zealand’s ban on selling e-cigarettes that deliver nicotine, their effectiveness as a smoking cessation aid, whether fears that e-cigarettes renormalise smoking are justified, and the safety of long-term use.  :

Reviewers:

Uditi Pandya, 3rd year student nurse, School of Nursing, The University of Auckland and Cynthia Wensley RN, Honorary Professional Teaching Fellow, The University of Auckland and PhD candidate, Deakin University, Melbourne cwensley@deakin.edu.au.

Summary of Results

Summary Of Results

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