Nicotine replacement is effective for smoking cessation
ACP J Club. 1994 July-Aug;121:19. doi:10.7326/ACPJC-1994-121-1-019
Silagy C, Mant D, Fowler G, Lodge M. The effectiveness of nicotine replacement therapies in smoking cessation. Online J Curr Clin Trials. 1994 Jan 14; Doc No 113:[7906 words; 110 paragraphs]. [Abridged version in Lancet. 1994 Jan 15;343:139-42.]
To assess the efficacy of nicotine replacement therapy (NRT) in achieving smoking cessation.
A computerized literature search was done using Data-Star in 7 databases (MEDLINE, CANCERLIT, Psychological Abstracts, Dissertation Abstracts, Health Planning and Administration, Social SciSearch, and Smoking and Health) from the time of inception of each database to March 1993. Search terms used were smoking, smoking cessation, randomized controlled trial, prospective, random allocation, and double-blind method. References of published reviews, clinical trials, and conference abstracts were reviewed; manufacturers of NRT preparations were contacted.
Studies were selected if they were randomized controlled trials that compared NRT (including gum, transdermal patch, nasal spray, and inhalers) with placebo or no therapy or compared different doses of NRT with at least a 6-month follow-up. 53 trials were identified; 42 of nicotine gum, 9 of transdermal patch, 1 of nasal spray, and 1 of inhaler.
Cessation rates at 1, 3, 6, and 12 months; level of nicotine dependence classified by score on the Fagerstr-m Tolerance Questionnaire; and odds of achieving abstinence in different settings and by intensity of nonpharmacologic treatment were extracted. The number needed to treat (NNT) for 1 person to achieve smoking abstinence at 12 months was calculated. Data were extracted independently by 2 persons.
Pooled cessation rates across all trials at the longest follow-up point available showed that 19% of participants who received NRT quit smoking compared with 11% in the control group (odds ratio [OR]1.71; 95% CI, 1.56 to 1.87). In participants with high levels of nicotine dependence, the OR of not smoking with 4-mg gum compared with 2-mg gum was 2.7 (CI, 1.48 to 4.99). The OR for abstinence was slightly greater when offered to participants recruited from the community or through special smoking clinics rather than from primary care settings or hospitals. The absolute probability of abstinence was greater in trials providing high-intensity nonpharmacologic treatment (20%) than in those with low-intensity treatment (11%), although the ORs for abstinence between levels of treatment intensity did not reach statistical significance.
Nicotine replacement therapy is effective in achieving smoking cessation. Success rates vary according to level of nicotine dependence, clinical setting, and intensity of nonpharmacologic treatment.
Sources of funding: Imperial Cancer Research Fund; Sir Robert Menzies Memorial Trust; Royal College of General Practitioners; Oxford Regional Health Authority.
For article reprint: Dr. C. Silagy, Department of General Practice, Flinders University of South Australia, School of Medicine, GPO Box 2100, AdelaideSA 5001, Australia. FAX 61 8 276 3305.
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, 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