RESUMO
INTRODUCTION AND OBJECTIVES: Counselling for tobacco quitting could be improved by informing smokers about the likelihood of success in quitting over time since the start of an intervention for smoking cessation. This study assessed the change in the probability of success in tobacco quitting during the course of two simple medical interventions for smoking cessation. METHODS: Prospective study in three worksites in the Basque Country (Spain), which underwent two interventions for quitting. Intervention 1 consisted of sporadic, brief (30 seconds-1 minute) and unstructured medical advice to quit. Intervention 2 consisted of brief (5-8 minutes) structured medical counselling for tobacco quitting in a first visit, followed by reinforcement advice on 3 occasions during 3 months, accompanied by nicotine patches individualized according to nicotine dependence. Results are expressed as a "relative measure of success" or rate of proportions (RP) calculated as the predictive value of achieving tobacco abstinence at 12 months for those with tobacco abstinence at 2 days, 15 days and 3 months from the start of each intervention divided by the percentage abstinent at 12. RESULTS: For the 103 smokers subjected to intervention 1, RP was 1.7 (CI 95%: 1.0-3.4) at 2 days, 2.3 (1.2-4.6) at 15 days, and 3.4 (1.8-6.5) at 3 months. For the 114 subjects who underwent intervention 2, RP was 1.3 (1.0-2.1) at 2 days, 1.9 (1.2-2.8) at 15 days, and 2.6 (1.8-3.8) at 3 months. Results did not change materially after stratification by number of cigarettes smoked, or nicotine dependence. CONCLUSIONS: Remaining abstinent from tobacco smoking at 3 months after the start of a quitting intervention increases the likelihood of success in quitting at 12 months.