Abstract
Clinical outcome studies of schizoaffective disorder patients have yielded conflicting results. One reason is the heterogeneity of samples drawn from the schizoaffective disorder population. Here, we studied schizoaffective disorder patients who showed marked functional impairment and continuous signs of illness for at least 6 months (i.e., DSM criteria B and C for schizophrenia). We assessed 176 chronic psychosis patients with a structured interview (SCID-IV-TR) and the Diagnostic Interview for Genetic Studies schizoaffective disorder module. We diagnosed 114 patients with schizophrenia and 62 with schizoaffective disorder. The two groups were similar with regard to age, gender, and race. We tested for group differences in antecedent risk factors, clinical features, and functional outcome. The schizoaffective disorder group differed from the schizophrenia group on two measures only: they showed higher rates of suicidality (more suicide attempts, p < 0.01; more hospitalizations to prevent suicide, p < 0.01) and higher anxiety disorder comorbidity (p < 0.01). When schizoaffective disorder patients meet DSM criteria B and C for schizophrenia, they resemble schizophrenia patients on several measures used to assess validity. The increased rate of anxiety disorders and suicidality warrants clinical attention. Our data suggest that a more explicit definition of schizoaffective disorder reduces heterogeneity and may increase validity.
Highlights
A recent meta-analysis of 50 studies comparing illness course and clinical outcomes in schizoaffective disorder, schizophrenia, and affective disorders reports the use of 10 different sets of diagnostic criteria for schizoaffective disorder [1]
A review of the schizoaffective disorder literature revealed that patients with schizoaffective disorder had a better outcome than those with schizophrenia when ICD-10 criteria were used, but not when DSM-IV criteria were used [2]
The schizoaffective disorder group did not differ from the schizophrenia group on two measures of premorbid function associated with the risk for psychosis: premorbid intellectual function, as assessed with Wechsler Test of Adult Reading (WTAR) (U = 3,288.00, p > 0.05), and years of education (U = 3,174.00, p > 0.05) (Table 4)
Summary
A recent meta-analysis of 50 studies comparing illness course and clinical outcomes in schizoaffective disorder, schizophrenia, and affective disorders reports the use of 10 different sets of diagnostic criteria for schizoaffective disorder [1]. A review of the schizoaffective disorder literature revealed that patients with schizoaffective disorder had a better outcome than those with schizophrenia when ICD-10 criteria were used, but not when DSM-IV criteria were used [2]. Schizophrenia and schizoaffective disorder are defined by three domains of psychopathology: psychosis, mood symptoms, and functional impairment. We display the schizophrenia population as an ellipsoid constrained by two diagnostic criteria: decrease of function below the level achieved prior to illness onset (criterion B) and disturbances lasting for at least 6 months (criterion C). Criteria B and C were added as gatekeepers during the DSM-III revision process, with the goal to exclude less severe cases and to increase the reliability and validity of schizophrenia [3]
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