It is not clear which patients with a first psychotic episode will develop schizophrenia. We performed a diagnostic follow-up of patients treated for a first time non-affective, non-schizophrenia psychosis and explored potential predictors of a subsequent schizophrenia or schizoaffective diagnosis.
This register-based cohort study comprises individuals born between 1973 and 1978 in Sweden, with a first hospital-treated psychosis excluding schizophrenia, schizoaffective disorder, bipolar disorder and depressive disorder with psychotic symptoms (n = 1840). The patients were followed for five years regarding subsequent diagnoses. Psychiatric, social, family history of psychiatric illness, premorbid intellectual level, head injuries and obstetrical complications were investigated by logistic regression as predictors of schizophrenia or schizoaffective diagnosis.
During the follow-up, 18% were diagnosed with schizophrenia or schizoaffective disorder, 5% were diagnosed with bipolar disorder, whereas 29% were not re-admitted to a psychiatric clinic. Patients with a first-degree relative hospitalized for schizophrenia and/or bipolar disorder had an increased risk of subsequent diagnosis for schizophrenia or schizoaffective disorder (odds ratio 1.9 and 95% confidence interval 1.1 to 3.0)), whereas previous severe criminality was associated with a decreased risk (odds ratio 0.5, 95% confidence interval 0.3–0.8).
Diagnostic outcome was diverse after a first non-schizophrenia and non-affective psychosis. Family history of severe mental illness and no previous conviction for severe criminality were the strongest risk factors for a future schizophrenia or schizoaffective diagnosis.
2013. Vol. 150, no 1, 205-210 p.