A 24-month prospective outcome study of first-episode schizophrenia and schizoaffective disorder within an early psychosis intervention program

Within the schizophrenia spectrum disorders, schizoaffective disorder is conventionally considered to have a better prognosis compared to schizophrenia. We tested the hypothesis that patients with first-episode schizoaffective disorder had better clinical and functional outcomes compared to patients with first-episode schizophrenia.

The study population consisted of consecutive subjects with first-episode schizophrenia or first-episode schizoaffective disorder (diagnosed according to DSM-IV criteria) enrolled in the national Early Psychosis Intervention Program at the Institute of Mental Health/Woodbridge Hospital in Singapore from March 2001 to March 2003. The subjects' level of psychopathology, insight, socio-occupational functioning, and quality of life were assessed using the Positive and Negative Syndrome Scale (PANSS), the Scale to Assess Unawareness of Mental Disorder, the Global Assessment of Functioning scale, and the World Health Organization Quality of Life-BREF scale, respectively, at baseline and at 6, 12, 18, and 24 months.

At baseline, patients with schizo-affective disorder (N = 24) were more likely to be employed (OR = 3.38, 95% CI = 1.27 to 9.02, p < .05), had a shorter duration of untreated psychosis (z = -3.30, p < .005), but had greater general psychopathology subscale scores on PANSS (z = -2.69, p < .01) compared to patients with schizophrenia (N = 254). Patients with schizophrenia had better insight into their psychiatric illness (z = -3.93, p < .001) at 6 months and expressed a better level of quality of life in the psychological health domain (z = -3.83, p < .001) at 12 months compared to patients with schizoaffective disorder. At 18 months, patients with schizoaffective disorder continued to have higher general psychopathology subscale scores on PANSS (z = -3.89, p < .001) compared to patients with schizophrenia.

Patients with first-episode schizoaffective disorder do not necessarily have less severe psychopathology or better longitudinal outcomes compared to patients with first-episode schizophrenia, a finding that warrants attention in the clinical management of these patients.