Is nicotine replacement therapy for smoking cessation effective in the "real world"? Findings from a prospective multinational cohort study.

BACKGROUND: Increasing smoking cessation rates is an important goal in preventing lung cancer and chronic obstructive pulmonary disease. Nicotine replacement therapy (NRT) has been found in clinical trials to improve the chances of success at stopping, but recent cross-sectional survey data have raised doubts as to whether it is effective when used by smokers making quit attempts unsupervised outside clinical trials. Because of biases inherent in cross-sectional surveys, this issue can only be adequately addressed using longitudinal studies. This paper reports the first study of its kind to examine the issue.
METHODS: The ATTEMPT cohort is a multinational cohort study with data collection by the internet which recruited smokers of > or = 5 cigarettes per day aged 35-65 years who were intending to stop smoking within the next 3 months. Phase 1 began in spring 2003 and involved 2009 smokers from the USA, UK, Canada and France. Phase 2 involved 3645 smokers and included the same countries plus Spain. Follow-up assessments were carried out every 3 months. 492 smokers who made a quit attempt without formal behavioural support or bupropion in the first 3-month follow-up period were identified from phase 1, 357 of whom were followed up for a further 6 months. The phase 2 sample involved 906 smokers making quit attempts, 732 of whom were followed up. At baseline, demographic characteristics, smoking history and nicotine dependence were assessed. Smokers who made quit attempts were questioned on methods used to aid them. The main outcome measure was self-report of complete abstinence throughout both the 3-month periods following the quit date.
RESULTS: 35.6% of smokers followed up in phase 1 and 29.6% of those followed up in phase 2 used NRT. The odds ratios comparing abstinence for 6 months in those using and those not using NRT, adjusting for nicotine dependence, were 3.0 (95% CI 1.2 to 7.5) for the phase 1 sample and 2.1 (95% CI 1.0 to 4.1) for the phase 2 sample. The difference in success rates between those using NRT and those not using it, adjusted for the Fagerstrom test for nicotine dependence (FTND) score, was 6% in the phase 1 sample and 3.7% in the phase 2 sample. The improved odds of success were not explicable in terms of motivation to use some form of aid to cessation or differential loss to follow-up.
CONCLUSION: NRT use by smokers making self-initiated quit attempts without formal behavioural support is associated with improved long-term abstinence rates.