The effects of a smoking cessation intervention on 14.5-year mortality - A randomized clinical trial

Background: Randomized clinical trials have not yet demonstrated the mortality benefit of smoking cessation. Objective: To assess the long-term effect on mortality of a randomly applied smoking cessation program. Design: The Lung Health Study was a randomized clinical trial of smoking cessation. Special intervention participants received the smoking intervention program and were compared with usual care participants. Vital status was followed up to 14.5 years. Setting: 10 clinical centers in the United States and Canada. Patients: 5887 middle-aged volunteers with asymptomatic airway obstruction. Measurements: All-cause mortality and mortality due to cardiovascular disease, lung cancer, and other respiratory disease. Intervention: The intervention was a 10-week smoking cessation program that included a strong physician message and 12 group sessions using behavior modification and nicotine gum, plus either ipratropium or a placebo inhaler. Results: At 5 years, 21.7% of special intervention participants had stopped smoking since study entry compared with 5.4% of usual care participants. After up to 14.5 years of follow-up, 731 patients died: 33% of lung cancer, 22% of cardiovascular disease, 7.8% of respiratory disease other than cancer, and 2.3% of unknown causes. All-cause mortality was significantly lower in the special intervention group than in the usual care group (8.83 per 1000 person-years vs. 10.38 per 1000 person-years; P = 0.03). The hazard ratio for mortality in the usual care group compared with the special intervention group was 1.18 (95% CI, 1.02 to 1.37). Differences in death rates for both lung cancer and cardiovascular disease were greater when death rates were analyzed by smoking habit. Limitations: Results apply only to individuals with airway obstruction. Conclusion: Smoking cessation intervention programs can have a substantial effect on subsequent mortality, even when successful in a minority of participants.