Abstinence from smoking eight years after participation in randomised controlled trial of nicotine patchBMJ 2003; 327 doi: http://dx.doi.org/10.1136/bmj.327.7405.28 (Published 03 July 2003) Cite this as: BMJ 2003;327:28
- Patricia Yudkin (), reader in medical statistics1,
- Kate Hey Yudkin, research officer2,
- Sarah Roberts Yudkin, research nurse2,
- Sarah Welch, research nurse2,
- Michael Murphy, director2,
- Robert Walton, senior research fellow3
- 1Department of Primary Health Care, University of Oxford, Institute of Health Sciences, Oxford OX3 7LF
- 2Cancer Research UK General Practice Research Group, Institute of Health Sciences, Oxford OX3 7LF
- 3Department of Clinical Pharmacology, University of Oxford, Radcliffe Infirmary, Oxford OX2 6HE
- Correspondence to: P Yudkin
- Accepted 6 March 2003
Few studies have investigated abstinence beyond three years among participants who stop smoking during trials of nicotine replacement therapy,1–3 and even fewer have followed up smokers who failed to quit during such trials. We carried out an eight year follow up of people who had participated in a randomised controlled trial of the nicotine patch.
Participants, methods, and results
Participants were the 1686 patients from general practices in Oxfordshire who took part in a double blind randomised controlled trial of the patch in 1991-2.4 5 At entry they smoked≥15 cigarettes a day and were aged 25–64 years. Participants wore the patches for 12 weeks. The main outcome was abstinence from smoking for one year, confirmed at 12, 24, and 52 weeks by a salivary cotinine concentration≤20 ng/ml (89% of cases) or expired carbon monoxide≤10 ppm (11%).
In 1999-2000, we contacted 1532 of the 1625 living participants. We sent two follow up letters and phoned non-responders. In total 840 participants completed a questionnaire giving demographic details and information about smoking. The mean time from enrolment in the trial to follow up was 8.3 (SD 0.35) years, with a range of 7.4-9.3 years. Responders were more likely to be women (59.0% v 51.7%; P=0.005) and were more likely to have stopped smoking during the trial than non-responders (13.2% v 5.5% quit for one year; P < 0.0001). Reported abstinence at follow up was confirmed by a plasma cotinine concentration≤20 ng/ml. Responders reported for how long they had been abstinent. We assumed that all those lost to follow up were still smoking.
Of the 153 participants who had stopped smoking for a year in the original trial, 83 were still not smoking at follow up, giving an eight year abstinence rate of 83/1625 (5%; 95% confidence interval 4% to 6%) and a relapse rate of 70/153 (46%; 38% to 54%) (table). Relapse was similar in active and placebo groups: the active/placebo odds ratio (OR) for continuous abstinence up to follow up was 1.39 (0.89 to 2.17; P=0.19) compared with 1.45 (1.04 to 2.03; P=0.03) for quitting for a year in the trial.
Of the 1472 who did not quit for a year in the trial, 116 (8%; 7% to 9%) were abstinent at follow up. Of these, 89 (6%; 5% to 7%) had abstained for a year or more, and 27 for less than a year (median 4 months). Overall at follow up therefore, 172 (11%; 9% to 12%) of trial participants had been abstinent for a year or more, 29 (2%) had been abstinent for less than a year, and 1424 (88%) were smoking.
Eight years after taking part in a randomised trial of the nicotine patch, just under half of the 9% who had stopped smoking for a year had relapsed, leaving 5% of all trial participants continuously abstinent for eight years. Previous studies have reported that a third to a half of all those who stop during a trial relapse by three or four years.1–3 Use of the nicotine patch conferred a 39% increase in the odds of continuous abstinence compared with placebo. The increase was not significant, but our original trial was not powered to detect the small difference observed in eight year abstinence rates (5.9% v 4.3%). Of the majority who did not quit in the trial, only 8% had given up smoking at follow up, leaving 88% of trial participants still smoking. Our estimates were based on the conservative but well accepted assumption that those lost to follow up were still smoking. Finding more effective ways to help people to give up smoking remains an ongoing challenge.
We thank Lesley Jones for computing help, and Elaine Johnstone and Sian Griffiths for cotinine analysis. Contributors: RW, PY, and MM conceived the study, wrote the protocol, and obtained funding. KH traced the participants and administered the study. SR and SW collected the patient data and took blood samples. PY supervised data analysis and interpretation, drafted the paper with contributions from all other authors, and is guarantor.
Funding Cancer Research UK. The guarantor accepts full responsibility for the conduct of the study, had access to the data, and controlled the decision to publish.
Competing interests None declared.
Ethical approval Anglia and Oxford Multicentre Research Ethics Committee, and 86 local research ethics committees.