Objectives: This study examined the relation between smoking and suicide, controlling for various confounders.
Methods: More than 50,000 predominantly White, middle-aged and elderly male health professionals were followed up prospectively with biennial questionnaires from 1986 through 1994. The primary end point was suicide. Characteristics controlled for included age, marital status, body mass index, physical activity, alcohol intake, coffee consumption, and history of cancer.
Results: Eighty-two members of the cohort committed suicide during the 8-year follow-up period. In age-adjusted analyses with never smokers as the comparison group, the relative risk of suicide was 1.4 (95% confidence interval [CI] = 0.8, 2.3) among former smokers, 2.6 (95% CI = 0.9, 7.5) for light smokers (< 15 cigarettes/day), and 4.5 (95% CI = 2.3, 8.8) among heavier smokers. After adjustment for potential confounders, the relative risks were 1.4 (95% CI = 0.9, 2.4), 2.5 (95% CI = 0.9, 7.3), and 4.3 (95% CI = 2.2, 8.5), respectively.
Conclusion: We found a positive, dose-related association between smoking and suicide among White men. Although inference about causality is not justified, our findings indicate that the smoking-suicide connection is not entirely due to the greater tendency among smokers to be unmarried, to be sedentary, to drink heavily, or to develop cancers.