A controlled trial of an expert system and self-help manual intervention based on the stages of change versus standard self-help materials in smoking cessation

Abstract

Aim: To examine the population impact and effectiveness of the Pro-Change smoking cessation course based on the Transtheoretical Model (TTM) compared to standard self-help smoking cessation literature.

Design: Randomized controlled trial.

Setting: Sixty-five West Midlands general practices.

Participants: Randomly sampled patients recorded as smokers by their general practitioners received an invitation letter and 2471 current smokers agreed.

Interventions: Responders were randomized to one of four interventions. The control group received standard self-help literature. In the Manual intervention group, participants received the Pro-Change system, a self-help workbook and three questionnaires at 3-monthly intervals, which generated individually tailored feedback. In the Phone intervention group, participants received the Manual intervention plus three telephone calls. In the Nurse intervention group, participants received the Manual intervention plus three visits to the practice nurse.

Measurements: Biochemically confirmed point prevalence of being quit and 6-month sustained abstinence, 12 months after study commencement.

Findings: A total of 9.1% of registered current smokers participated, of whom 83.0% were not ready to quit. Less than half of participants returned questionnaires to generate second and third individualized feedback. Telephone calls reached 75% of those scheduled, but few participants visited the nurse. There were small differences between the three Pro-Change arms. The odds ratio (95% confidence intervals) for all Pro-Change arms combined versus the control arm were 1.50 (0.85-2.67) and 1.53 (0.76-3.10), for point prevalence and 6-month abstinence, respectively. This constitutes 2.1% of the TTM group versus 1.4% of the control group achieving confirmed 6-month sustained abstinence.

Conclusions: There was no statistically significant benefit of the intervention apparent in this trial and the high relapse of quitters means that any population impact is small.