The effect of risky alcohol use and smoking on suicide risk: findings from the German MONICA/KORA-Augsburg Cohort Study.

BACKGROUND: Smoking and heavy alcohol use predicts suicidal behaviour. Whether the simultaneous presentation of both conditions induces an amplified effect on risk prediction has not been investigated so far. METHODS: In a community-based cohort study, a total of 12,888 subjects (6,456 men, 6,432 women; age range of 25-74 years at assessment) from three independent population-based cross-sectional MONICA surveys (conducted in 1984/85, 1989/90, and 1994/95), representative for the Southern German population, was followed up until 31 December 2002. Standardized mortality ratios (SMR) for deaths from suicide using German population rates were calculated for smoking and high alcohol consumption. RESULTS: After a mean follow-up time of 12.0 (SD 4.4) years and 154,275 person-years at risk, a total of 1,449 persons had died from all causes and 38 of them from suicide. Compared to the general population, mortality from suicide was increased for risky alcohol consumption (SMR = 2.37; 95% CI 1.14-4.37) and for smoking (SMR = 2.30; 95% CI 1.36-3.63). A substantial increase in suicide mortality (SMR = 4.80; 95% CI 2.07-9.46) was observed for smokers with risky alcohol consumption. CONCLUSIONS: The approximately fourfold increased relative risk for completed suicide in subjects with smoking and risky alcohol consumption indicates a synergistic effect which deserves an increased alertness.