The descriptive epidemiology of unnatural deaths in Oregon's state institutions: a 25-year (1963-1987) study. II. Analysis of the incidence rate and its many variations.

We have analyzed suicide data of the Forensic Psychiatric Program of the Oregon State Hospital in terms of the various ways of expressing occurrence rates that are found in the literature. All of these rates are ultimately based upon either (a) the average daily population, computed from occupancy rates of institutional beds, or (b) a measure of the total number of individuals at risk (that is, all who were in the study population during the time frame of the study). We discuss reasons for the use of these different rates. We have also calculated the risk of suicide for each of two factors: (a) the primary psychiatric diagnosis and (b) the type of legal commitment under which these patients were admitted to the Forensic Psychiatric Program. We discovered that virtually the entire risk of suicide in this program was borne by patients whose primary diagnosis was that of chronic schizophrenia and who were committed there because of diminished criminal responsibility for a crime of which they were found guilty in a court of law.