Psychometric characteristics of the Scale for Suicide Ideation with psychiatric outpatients

The psychometric properties of the Scale for Suicide Ideation--Current (SSI-C; Beck, Kovacs & Weissman, 1979, Journal of Consulting and Clinical Psychology, 47, 343-352) and the Scale for Suicide Ideation--Worst (SSI-W; Beck, Brown, Steer, Dahlsgaard & Grisham, 1997, in press) were explored. These 19-item clinician-administered scales measure current suicide ideation (SSI-C) as well as suicide ideation at its worst point in the patient's life (SSI-W). For a sample of 4063 outpatients, both scales were positively correlated with a diagnosis of a principal mood disorder, a diagnosis of a personality disorder, and measures of depression and hopelessness. The relationship between the SSI-W and a history of suicide attempts was stronger (r = 0.50, P < 0.001) than the relationship between the SSI-C and previous suicide attempts (r = 0.31, P < 0.001). For 444 current and 1764 past suicide ideators, the SSI-C and the SSI-W had high internal consistencies (coefficient alpha s = 0.84 and 0.89, respectively). The SSI-C and the SSI-W were moderatedly correlated with each other (r = 0.51, P < 0.001). Iterated maximum-likelihood principal-factor analyses identified comparable Preparation and Motivation dimensions underlying both scales.