The association between the duration of untreated psychosis (DUP) and outcome of schizophrenia may be confounded by other factors such as poor pre-morbid adjustment. The aim of the present study was to examine the independent contributions of DUP and of pre-morbid adjustment to the clinical and social outcomes of schizophrenia.
A longitudinal, prospective, 2-year follow-up study of 423 patients with first-episode schizophrenia-spectrum psychosis was conducted. Patients were comprehensively assessed at entry, 1-year and 2-year follow-up. At entry, DUP was measured by IRAOS (an instrument for the assessment of onset and early course of schizophrenia) and pre-morbid adjustment was measured by the Pre-morbid Adjustment Scale (PAS) as ‘pre-morbid social adaptation’ and ‘pre-morbid school adaptation’. Outcome measures included the Scale for the Assessment of Positive Symptoms (SAPS), the Scale for the Assessment of Negative Symptoms (SANS), the Social Network Schedule and social information. Multiple linear regression models were used for data analysis.
The median DUP was 48 weeks, which is long compared to other studies. Longer DUP was independently associated with more psychotic symptoms at entry, 1-year and 2-year follow-up. Poorer pre-morbid social adaptation was independently associated with more negative symptoms and smaller social network at entry and 1-year follow-up. Poorer pre-morbid school adaptation was independently associated with poor vocational outcome at 1-year and 2-year follow-up.
Longer DUP is associated with poorer 2-year outcome of psychosis in schizophrenia-spectrum disorders, when pre-morbid functioning and other prognostic factors are controlled for. Impaired pre-morbid development is independently associated with more negative symptoms and poorer social outcome.