Previous Suicide Attempt and Its Association With Method Used in a Suicide Death

Non-fatal suicide attempts are a risk factor for suicide, but less is known about its effect on the method of injury used in an eventual suicide death. This study examines the association between history of non-fatal suicide attempt and the risk of a poisoning suicide versus firearm or hanging suicide in Colorado.

Nine years (2004-2012, N=7,020) of suicide deaths in Colorado were compiled through the National Violent Death Reporting System. With these data, a retrospective cohort study was conducted in 2015, examining the risk associated with a history of suicide attempt and an eventual suicide death by poisoning versus a firearm or hanging suicide death. Multivariable log-binomial regression modeling was used to analyze the possible confounders of age and county type and gender as an effect modifier.

Suicide decedents with evidence of prior suicide attempt were twice as likely to eventually die by suicide via self-poisoning rather than by firearm injury (relative risk=1.94, 95% CI=1.8, 2.1, p<0.001). A significant interaction (p<0.001) between prior attempt and gender was identified and the relationship between prior attempt and method (poisoning versus firearm) was stronger among male than female suicides (female attempt history, 1.16, 95% CI=1.07, 1.27, p<0.001; male attempt history, 1.91, 95% CI=1.69, 2.16, p<0.001).

Individuals with a history of non-fatal suicide attempt are more likely to die by suicide via poisoning rather than firearm. Gender has a significant effect on this association. This information can be useful when discussing means restriction and suicide prevention efforts.