The InterSePT suicide scale for prediction of imminent suicidal behaviors

The present study examined the ability of the International Suicide Prevention Trial (InterSePT) Scale for Suicidal Thinking (ISST) and the Calgary Depression Scale (CDS) to predict suicide attempts or hospitalizations to prevent attempts (referred to as Type 1 events) during the InterSePT trial [Meltzer, H.Y., Alphs, L., Green, A.I., Altamura, A.C., Anand, R., Bertoldi, A., Bourgeois, M., Chouinard, G., Islam, M.Z., Kane, J., Krishman, R., Lindenmayer, J.P., Potkin, S., 2003. Clozapine treatment for suicidality in schizophrenia. Archive of General Psychiatry 60, 82-91]. The primary goal of this analysis was to determine if the ISST and CDS ratings indicated that the raters, an unblinded (UP) and a blinded psychiatrist (BP) using the ISST, and a blinded rater using the CDS, were able to identify those patients who had a Type 1 event. The ratings of patients adjudged to have experienced a Type 1 event (Group 1) were compared with patients who did not (Group 2). The ISST and the CDS ratings obtained 2-8 weeks prior to a Type 1 event (Pre-1) and Pre-2, the rating immediately prior to Pre-1, obtained 2-12 weeks before Pre-1, were analyzed to test the hypothesis that the difference between Pre-2 and Pre-1 ratings for the Group 1 patients was significantly greater than the difference in the comparable ratings for Group 2 patients. The prediction that patients with Type 1 events would show greater worsening in ISST and CDS ratings between Pre-2 and Pre-1 than the Group 2 patients was confirmed. However, the sensitivity and specificity of a worsening in ratings was not sufficient to provide definitive warning of an impending Type 1 event. Other characteristics of the patients with Type 1 events provide additional warning: e.g. overall higher ratings on these scales, slower improvement in suicidality during treatment, and previous number of suicide attempts. These results indicate that the ISST and CDS may provide some additional information that can assist clinical decision making regarding suicidal risk in patients with schizophrenia or schizoaffective disorder.