A population-based longitudinal study of suicide risk in male schizophrenia patients: Proximity to hospital discharge and the moderating effect of premorbid IQ

Suicide is a major cause of death in schizophrenia. Identifying factors which increase the risk of suicide among schizophrenia patients might help focus prevention efforts. This study examined risk of suicide in male schizophrenia patients using population-based data, examining the timing of suicide in relation to the last hospital discharge, and the effect of premorbid IQ on risk of suicide. Data on 930,000 male adolescents from the Israeli military draft board were linked with data from the Israeli Psychiatric Hospitalization Case Registry and vital statistics from the Israeli Ministry of Health. The relationship between premorbid IQ and risk for suicide was examined among 2881 males hospitalized with schizophrenia and compared to a control group of 566,726 males from the same cohort, who were not hospitalized for a psychiatric disorder, using survival analysis methods. Over a mean follow-up period of 9.9 years (SD=5.8, range: 0-22 years), 77/3806 males with schizophrenia died by suicide (a suicide rate of 204.4 per 100,000 person-years). Approximately 48% of the suicides occurred within a year of discharge from the last hospital admission for schizophrenia. Risk of suicide was higher in male schizophrenia patients with high premorbid IQ (HR=4.45, 95% CI=1.37-14.43) compared to those with normal premorbid IQ. These data indicate that male schizophrenia patients with high premorbid IQ are at particularly high risk of suicide, and the time of peak risk is during the first year after the last hospitalization discharge.