Predictive Validity of the Suicide Probability Scale in a Male Inmate Population

This paper describes the predictive power of the Suicide Probability Scale (SPS) within a male inmate population. The SPS scores of 1,047 inmates from 1995 to 1996 were compared against their suicidal behaviors in the following 10 years. The SPS probability score and the scores on its four subscales were found to be significantly higher in the group that engaged in at least one of three types of suicidal behavior: suicide, non-lethal self-harm and serious suicidal intentions. However, the SPS did not discriminate the inmates who went on to commit suicide. The SPS’s capacity to predict suicidal behavior proved limited in terms of sensitivity. In this regard, the SPS’s low and high risk levels correctly identified 36% of inmates who later engaged in suicidal behavior. The specificity was 0.85. These results confirm the SPS’s predictive power with male prisoners. These findings are the first to demonstrate the predictive validity of the SPS.