Suicide risk in older adults: evaluating models of risk and predicting excess zeros in a primary care sample.

Research is needed that examines theory-based risk factors for suicide in older adults. The interpersonal theory of suicide (Joiner, 2005; Van Orden et al., 2010) provides specific hypotheses regarding variables that contribute to the development and variability in death ideation and suicide ideation; however, data suggest that older adults may not report suicide ideation in research settings or to treatment providers even when they experience it (Heisel et al., 2006). The purpose of this study was to test theory-based predictions regarding variables that contribute to death ideation (i.e., a passive wish to die) and suicide ideation in older adults. This study introduces the application of zero-inflated negative binomial regression (ZINB) to the study of suicidal behavior. ZINB was used to test theory-based predictions, while also testing a hypothesis regarding variables associated with denial of suicide ideation among participants who endorsed risk factors associated with suicide risk. Participants included 239 adults aged 60 and older recruited from primary care clinics who completed a variety of self-report instruments. The results of this study indicated that perceived burdensomeness and hopelessness were significantly associated with variability in death ideation. Additional results indicated that elevated scores on thwarted belonging, the interaction between perceived burdensomeness and hopelessness, and the interaction between thwarted belonging and perceived burdensomeness were associated with a significant reduction in the probability of a participant being a suicide ideator. These results offer substantial support for the interpersonal theory of suicide. The implications of these findings are discussed.