Risk factors for completed suicide in schizophrenia and other chronic psychotic disorders: a case-control study.

OBJECTIVE Despite an increased risk for suicide among individuals diagnosed with psychotic disorders, risk factors for completed suicide remain largely unexamined in this population. Using a case-control design, this study aimed to investigate clinical and behavioural risk factors for suicide completion in schizophrenia and other chronic psychotic disorders. METHOD A total of 81 psychotic subjects were examined; of these, 45 died by suicide. Proxy-based interviews with, on average, 2 informants were conducted using the SCID I and II interviews and a series of personality trait assessments. RESULTS Psychotic individuals at risk for suicide are most readily identified by the presence of depressive disorders NOS, moderate to severe psychotic symptoms and a family history of suicidal behaviour. They also exhibited fewer negative symptoms, had more comorbid diagnoses and, contrary to findings in other populations, we found that cluster A and C personality trait symptoms seem to have protective effects against suicide in schizophrenics and other chronic psychotic suicides. CONCLUSIONS Our study suggests that behavioural mediators of suicide risk, such as impulsive-aggressive behaviours, do not play a role in schizophrenic and chronic psychotic suicide. This is contrary to findings in other diagnostic groups, thus implying heterogeneity in predisposing mechanisms involved in suicide.