Risk factors for completed suicide in schizophrenia

Schizophrenic patients in Taiwan have lower comorbidity of substance use disorders than do those in Western countries, and most of them live with their families. This study investigated the risk factors for completed suicide in this population with inherently lower rates of the confounding variables of substance abuse and social isolation.

4237 acute inpatients with DSM-III, DSM-III-R, or DSM-IV schizophrenia admitted from January 1, 1985, to December 31, 2000, were followed through 2001 by record linkage to the Death Certification System. Seventy-eight subjects who died from suicide during this period were matched with living controls randomly for age (+/- 5 years), sex, and the same year of index admission. Demographic and clinical variables were collected from medical records and formally confirmed at every admission and outpatient follow-up.

Among 78 case-control pairs, the lifetime prevalence of substance use disorders was 7.1%, and 93.6% of the subjects lived with their families. Approximately half of the completed suicides occurred within 4 years after the first admission. Conditional logistic regression analysis revealed a strong association with the following 3 variables: depressive syndrome in residual phase (adjusted odds ratio [OR] = 23.07, p < .005), higher suicide intensity (adjusted OR = 2.78, p < .05), and later age at onset (increase per year, adjusted OR = 1.07, p < .05). Fasting cholesterol level and clozapine use had no association with completed suicide.

The peak period for completed suicide was early years after the first admission. The target population for additional measures to prevent suicide should include patients with depressive syndrome in residual phase, higher suicide intensity, and later onset of illness.