Nicotine replacement is effective for smoking cessation
ACP J Club. 1994 July-Aug;121:18. doi:10.7326/ACPJC-1994-121-1-018
Tang JL, Law M, Wald N. How effective is nicotine replacement therapy in helping people to stop smoking? BMJ. 1994 Jan 1;308:21-6.
To assess the efficacy of nicotine replacement therapy (NRT) in persons attempting to quit smoking.
MEDLINE and Index Medicus were searched, the bibliographies of relevant trials and review articles were reviewed, and experts in the field were consulted.
Studies were selected if they were randomized controlled trials of nicotine replacement therapy with at least a 6-month follow-up; 37 trials were found. 27 trials were of nicotine gum, 2 mg, compared with placebo gum or no gum; 6 trials were of nicotine gum, 4 mg, compared with 2-mg gum or placebo; and 6 trials were of nicotine transdermal patch compared with placebo patch.
Efficacy was defined as the difference between percentages of treated and control participants who had stopped smoking at 1 year. In applicable trials, smokers were classified for high and low degrees of nicotine dependence according to the Fagerström Tolerance Questionnaire. Results were also stratified by trial setting (self-referred participants and invited participants).
For nicotine gum, 2 mg, compared with placebo gum or no gum, the difference in smoking cessation rates was 6% (95% CI, 4% to 8%). In the 6 trials that measured nicotine dependence, the effect of the 2-mg gum was restricted to those with a high degree of nicotine dependence. The difference between active therapy and placebo in high-dependence smokers was 16% (CI for the difference, 7% to 25%) and 2% in low-dependence smokers (CI for the difference, -7% to 10%) (P < 0.02 for the difference between effect sizes). 2-mg nicotine gum had a larger effect in self-referred participants compared with invited participants (11% [CI, 7% to 16%] vs. 4% [CI, 2% to 5%]; P < 0.001 for the difference between the 2 effect sizes). 4-mg gum was more effective than 2-mg gum in high-dependence smokers (difference in smoking cessation rates, 21%; CI, 9% to 32%). For transdermal patch compared with placebo patch, the difference in efficacy was 9% (CI, 6% to 13%). In studies that measured nicotine dependence, no difference was noted in the efficacy of patches between high- and low-dependence smokers.
Nicotine gum and nicotine transdermal patch were effective in helping people quit smoking, with higher doses showing greater effect, especially in smokers with high levels of nicotine dependence.
Source of funding: The Department of Health (United Kingdom).
For article reprint: Not available.
The meta-analyses by Tang and Silagy and their colleagues provide clear evidence that NRT is more effective than placebo or no nicotine replacement as an intervention for smoking cessation. Although both studies can be criticized for not evaluating the quality of the trials included in the meta-analyses, their overall findings are consistent with previous reviews of the efficacy of NRT (1, 2). NRT almost doubles the rate of abstinence achieved with placebo or control treatment in a wide variety of clinical settings and populations of smokers.
Assessing a patient's level of nicotine dependence can help guide treatment decisions. Smokers with a high level of nicotine dependence are more likely to benefit from nicotine gum than are smokers with low levels of dependence, and highly dependent smokers are more likely to benefit from 4-mg than from 2-mg gum. Although there is little evidence to suggest that the efficacy of nicotine patches is related to the degree of nicotine dependence, nicotine patches produce a slow increase and a stable blood level of nicotine and, therefore, may be less likely than nicotine gum to satisfy highly dependent smokers who see the "bolus effect" produced by smoking cigarettes. Although not proven empirically, patients with very high levels of dependence may benefit from combined patch and gum treatment or concurrent use of > 1 patch, especially if they have failed previous NRTs.
The absolute rates of abstinence achieved with NRT vary considerably depending on the population of smokers studied, the intensity of the additional smoking cessation treatment provided, and characteristics of the clinical setting. Using data from the study by Silagy and colleagues, the pooled abstinence rates for active nicotine gum were 11% in primary care settings and 36% in specialized smoking cessation clinics. This difference is probably attributable to the participation of smokers who are more motivated and the provision of more intensive behavioral treatment in clinic-based studies. Although the absolute difference in abstinence rates between NRT and control in primary care settings is only a few percentage points, the public health implications of achieving this effect among the large proportion of smokers who visit physicians each year are enormous.
NRT should only be prescribed for patients who are ready to quit smoking. Providing personalized information and feedback and encouraging patients to think about the effects of smoking are interventions physicians can use to help patients who are not yet prepared to quit (3).
Transdermal patches are the NRT of choice in primary care settings because they have been shown to be effective in placebo-controlled trials when provided with limited support, in contrast to the nicotine gum trials. When compared with gum, patches are easier to use, have less disturbing side effects, and appear to have a lower risk for long-term dependence. Because several studies have shown that the effect of NRT can be enhanced by the addition of behavioral counseling (4), physicians should always provide self-help materials and follow-up for patients receiving NRT.
Michael G. Goldstein, MD
Brown University School of Medicine Providence, Rhode Island, USA