IJE Advance Access originally published online on August 19, 2005
International Journal of Epidemiology 2005 34(5):1001-1003; doi:10.1093/ije/dyi171
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Cochrane Column |
Cochrane Column
South African Cochrane Centre, Medical Research Council, PO Box 19070, Tygerberg 7505, South Africa. E-mail: taryn.young{at}mrc.ac.za
The aim of the Column is to highlight Cochrane systematic reviews of relevance to public health and to stimulate debate on relevance, feasibility, and acceptability. The Cochrane Collaboration (http://www.cochrane.org) is an international, non-profit organization that prepares and disseminates up-to-date systematic reviews on the effects of healthcare interventions in order to help people make well-informed decisions. Systematic reviews aim to answer focused healthcare questions by systematically identifying and evaluating all relevant research studies and synthesizing their results.
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Nicotine replacement therapy for smoking cessation: Cochrane systematic review
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Background |
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Nicotine replacement therapy (NRT) is designed to assist smokers to quit smoking by reducing the withdrawal symptoms experienced by nicotine-dependent smokers who are abstaining from smoking. Nicotine can be delivered through the oral mucosa using gum, lozenges, sublingual tablets and inhalers, or via a transdermal patch, or nasal spray. This review evaluated the efficacy of all forms compared with placebo or no intervention. The review also reviewed the evidence on higher-dose products, combinations of products, and the relative effects with different levels of behavioural support.
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Methods |
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Randomized or quasi-randomized trials comparing any type of NRT with placebo, no treatment or an alternative type or dose of NRT were identified from the specialized trials register of the Cochrane Tobacco Addiction group in March 2004. Two authors extracted data independently. Data extracted included the numbers randomized, numbers quit at longest follow-up, NRT type, dose and duration of use, and level of behavioural support. The strictest definition of quitting was selected, and randomized participants lost to follow-up were assumed to be continuing smokers.
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Results |
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One hundred and twenty-three trials were included of which 103 contributed to the primary comparison. All types of NRT significantly increased the odds of quitting, and there was little difference between them (Table 1). Four milligrams was more effective than 2 mg gum for highly dependent smokers. There might be a small benefit of doubling the normal patch dose in highly dependent smokers. There was some evidence that a combination of nicotine patch and a form allowing ad lib dosing increased quit rates. There was no evidence for a difference between 18 and 24 h patch types, or for any benefit of gradual weaning of the dose at the end of treatment. The relative benefit of NRT was similar whether brief or intensive behavioural support was provided. Absolute quit rates were generally higher when NRT was combined with behavioural support.
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Discussion |
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NRT helped motivated smokers sustain a successful quit attempt, although relapse was still common and the percentage of successful quitters after 6–12 months was low. Intensive behavioural support is not a requirement for success, but smokers attempting to quit without additional support need to follow instructions for correct use of products. Choice of type is likely to depend on individual preference. The adverse effects depend on the type used; irritation to the oral mucosa may occur with oral and nasal dosing forms, and skin irritation may occur with patch use. Use of a combination of types, or an increased number of patches, may be helpful for dependent smokers who have been unable to quit using standard treatment regimes. NRT is safe for use by smokers with stable cardiovascular disease.
The full text of the Cochrane Review is available in The Cochrane Library. Silagy C, Lancaster T, Stead L, Mant D, Fowler G. Nicotine replacement therapy for smoking cessation. The Cochrane Database of Systematic Reviews 2004, Issue 3. Art. No.: CD000146 [GenBank] .pub2. doi: 10.1002/14651858.CD000146.pub2. This version first published online: 19 July 2004 in Issue 3, 2004. Date of most recent substantive amendment: 07 April 2004.
Commentary: Nicotine replacement therapy for smoking cessation
Department of Psychiatry, University of Vermont, Burlington 05401-1419, USA
Although meta-analyses focus on pooling results to determine if a treatment is reliably efficacious, another method is to examine replicability across trials. In the Cochrane nicotine replacement therapy (NRT) review, 100 of 104 randomized controlled trials (96%) of NRT had an odds ratio (OR) of >1.0. What other treatment do we have that is effective in 96% of trials?
Treatment of non-nicotine drug dependencies usually assumes talking therapy is essential and many have thought that NRT without such therapy would be ineffective; however, the Cochrane review clearly shows NRT increases the odds of quitting 1.5–2.0-fold independent of the amount of adjunctive therapy; e.g. even in the complete absence of therapy i.e. over the counter (OTC). Talking therapies do increase overall quit rates but even when provided free of charge, 97% of smokers will not attend such treatment in person or via phone. As a result, OTC NRT is by far the most common treatment for smoking cessation (i.e. used in 20% of quit attempts in the US). Cochrane and other reviews find the absolute increase in quitting with OTC NRT to be 
5%. This may seem small, but because smoking is such a potent risk factor, even a 5% reduction in smoking prevalence is probably more cost-effective in preventing deaths than most public health interventions.1
Unfortunately, even in the US where OTC NRT is readily available, over half of smokers never quit. This has led many to suggest using NRT to reduce cigarettes/day in unmotivated smokers and, thereby, reduce the harm from smoking. Whether this will occur is unclear owing to compensatory smoking. However, both this Cochrane review and a larger review2 have shown that using NRT to help unmotivated smokers to reduce smoking is safe and, importantly, significantly increases the probability they will later quit. Thus, using NRT to reduce smoking in ongoing smokers may become common, not to reduce risk, but to motivate cessation.
Finally, although many believe prevention or public smoking policies are more effective tobacco control strategies than treatment for smoking, if one examines the Cochrane and other meta-analyses, to this author, the quality and amount of evidence and the consistency and magnitude of results are strikingly superior for two interventions—NRT and taxes—compared with interventions such as school prevention programmes, community coalitions, worksite restrictions, media, restricting sales, etc. Raising taxes on cigarettes and subsidizing some of the cost of OTC NRT may be the most important tobacco control strategies, especially for countries with few resources.
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1 Murray JL, Lopez AD. Global mortality, disability and the contribution of risk factors: Global Burden of Disease Study. Lancet 1997;349:1436–15.[CrossRef][ISI][Medline]
2 Hughes JR, Carpenter MJ. The feasibility of smoking reduction: an update. Addiction 2005;100:1074–89.[CrossRef][ISI][Medline]
Commentary: Nicotine replacement therapy for smoking cessation
Smoker's Informations Centre, Helsinborg, Sweden
It is with great pleasure that this lazy clinician and scientist welcomes the latest Cochrane review. As usual it is done with great meticulousness, care, and sense. Anything more complete is difficult to imagine. Personally I find these reviews very useful; (i) in deciding treatment for my smokers, (ii) for making slides for presentations, or (iii) for having a convenient access to the literature in the area.
As with all reviews the problem is selective publishing but the authors addressed this area and they are also so close to the science of tobacco dependence that they have a good feel for what is missing and are discussing it well.
One of the strengths of this review is that it is applicable to most clinicians regardless of circumstance, whether there is time for only a brief intervention or a full specialist approach. I would also think that the recommendations are relatively applicable to all countries whether they are highly economically developed or in the so-called third world. The frustration I can sense from the poorer countries or those with a less developed anti-smoking climate, is that the reviewed products may not be available on the market.
In the area of smoking reduction or harm reduction, which is currently very much discussed, I would have liked to see more of the recent studies included. Only three studies are included but over the last years several others have been published, although just as posters. In the category, ‘Effect of pre-treatment with NRT’, there is also data imbedded in Herrera et al.'s 19951 study that could have been discussed.
All in all, this review can be highly recommended for all professionals with an interest in knowing the state of the art in how NRT should most effectively be used in the treatment of tobacco smoking.
| A summary of Cochrane reviews (and protocols) of relevance to health promotion and public health can be viewed on the Cochrane Health Promotion and Public Health website: http://www.vichealth.vic.gov.au/cochrane/
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References |
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1 Herrera N, Franco R, Herrera L, Partidas A, Rolando R, Fagerstrom KO. Nicotine gum, 2 and 4 mg, for nicotine dependence. A double-blind placebo-controlled trial within a behavior modification support program. Chest 1995;108:447–51.
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  M. R. MunafU Harm reduction: lessons learned from tobacco control J Psychopharmacol, May 1, 2006; 20(3): 329 - 330. [PDF]
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