Suicidal Behavior in Relatives or Associates Moderates the Strength of Common Risk Factors for Suicide.

The prevalence and odds ratios of different suicide risk factors were compared in three pairs of decedents: 80 suicides and 25 injury decedents with blood relatives with suicidal behavior history (biologically exposed); 259 suicides and 126 injury decedents with unrelated acquaintances with suicidal behavior history (socially exposed); and 471 suicides and 523 injury decedents with neither relatives nor acquaintances with suicidal behavior history (unexposed). Negative life events and high psychological stress were more common in socially exposed suicides than in other suicides. The adjusted odds ratios of most established suicide risk factors were higher in unexposed decedents than in biologically or socially exposed decedents, suggesting that the predictive value of established risk factors wanes in individuals who have been exposed to suicidal behavior in family or friends.