Background: Earlier studies of patients with schizophrenia have investigated suicide risk in relation to specific psychiatric symptoms, but it remains to be better understood how suicide risk relates to the diagnostic profile in these patients.
Methods: We identified all patients with a first clinical ICD-diagnosis of schizophrenia, schizophreniform or schizoaffective disorder in Stockholm County between 1984 and 2000. Patients who died by suicide within five years from diagnosis were defined as cases (n=84) and were individually matched with a similar number of living controls from the same population. Sociodemographic and clinical variables were retrieved from hospital records through a blind process. DSM-IV lifetime diagnoses for cases and controls were derived using the OPCRIT algorithm.
Results: A schizophrenia spectrum diagnosis (i.e. schizophrenia, schizophreniform or schizoaffective disorder) was assigned by OPCRIT to 50% of the suicide cases and 62% of the controls. Criteria for schizophrenia were met by 41% of the cases and 51% of the controls; for schizoaffective disorder by 8% of the cases and 10% of the controls; for other psychosis by 23% of the cases and 25% of the controls; and for mood disorder by 26% of the cases and 12% of the controls. Using the schizophrenia diagnosis as a reference, suicide risk was significantly higher in patients meeting criteria for a mood disorder diagnosis with an adjusted odds ratio of 3.3 (95% CI 1.2-9.0).
Conclusion: In patients with a clinical schizophrenia spectrum diagnosis, a DSM-IV mood disorder diagnosis increases the suicide risk more than three-fold.
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