Motivating smokers to quit using computer-generated letters that target either reduction or cessation: A population-based randomized controlled trial among smokers who do not intend to quit

Background This study examined the long-term efficacy of individualized counseling letters that targeted either smoking abstinence or reducing the number of cigarettes smoked per day to promote future cessation. Methods A nationwide random-digit-dialing telephone sample was used to identify smokers from the general adult population (participation proportion: 54.5%). In total, 1462 participants (48% female) who did not intend to quit within the next six months and who smoked ten or more cigarettes a day were randomized to one of two intervention groups or an assessment-only control condition. The interventions consisted of three tailored letters that were sent after baseline and follow-up assessments after three and six months. Follow-up data on smoking status were provided by 82% and 77% of the participants 12 and 24 months after study inclusion, respectively. Generalized estimation equation (GEE) models adjusted for potential baseline confounders and multiple imputation of missing follow-up data were used to estimate intervention effects. Results At 24-month follow-up prevalence of 7-day point abstinence was 8.4%, 12.9% and 14.7% in the control, abstinence intervention and reduction intervention condition, which corresponds to a number needed to treat of 22 (95%-CI: 11–707) and 16 (95%-CI: 9–53). Adjusted GEE analyses revealed that the smoking reduction intervention (OR_adj = 2.3, p < 0.01) but not the abstinence intervention (OR_adj = 1.4, p = 0.20) increased the odds of 6-month prolonged abstinence compared with the control condition. No significant differences appear when directly comparing both intervention groups. Conclusion Smoking reduction should be considered as an alternative intervention goal for smokers who are unable or unwilling to quit.