Independent association of chronic smoking and abstinence with suicide

The study examined whether chronic exposure to nicotine is independently associated with suicide.

Data from the 1993 National Mortality Followback Survey in the United States were analyzed by using a case-control design. Data for 989 suicide decedents were compared with data for 3,125 accident and homicide decedents. Inclusion criteria were ever smoking 100 cigarettes and white or black race. The exclusion criterion was death from natural or undetermined causes. Three smoking parameters were compared: lifetime smoking duration, ever quitting, and abstinence duration. Covariates were the manner of death, which was derived from coroners' death certificates, and data pertaining to the last year of life, which was reported by next of kin, on depressive symptoms, alcohol and drug use, veteran status, having a firearm in the home, and living alone.

In multivariate, fully adjusted analyses, longer lifetime smoking (≥ 41 versus ≤ 10 years) was associated with higher odds of suicide (odds ratio [OR]=2.26, 95% confidence interval [CI]=1.30-3.93). Quitting smoking was associated with lower odds of suicide (OR=.37, CI=.25-.55), as was longer abstinence duration (≥ 11 versus <5 years) (OR=.33, CI=.21-.52). These associations were observed only among males.

Findings indicated a probable independent association between suicide and current smoking and longer lifetime smoking duration. The findings are additional grounds to investigate smoking as a possible independent cause of suicide.