To what extent does symptomatic improvement result in better outcome in psychotic illness?

Background. The effectiveness of therapeutic interventions in psychosis is increasingly reported in terms of reductions in different symptom dimension s. It remains unclear, however, to what degree such symptomatic changes are accompanied by improvement in other measures such as service use, quality of life, and needs for care. Methods. A sample of 708 patients with chronic psychotic illness was assess ed on three occasions over 2 years (baseline, year 1 and year 2). A multile vel analysis was conducted to examine to what degree reduction in psychopat hological scores derived from factor analysis of the Comprehensive Psychopa thological Rating Scale (CPRS), was associated with improvement in service use, disability, subjective outcomes and measures of self-harm. Results. Reduction in positive, negative, depressive and manic symptoms ove r the study period were all independently associated with lessening of soci al disability. Reduction in negative symptoms, and to a lesser extent in po sitive and manic symptoms, was associated with less time in hospital and mo re time living independently, whereas changes in positive and manic symptom s resulted in fewer admissions. Subjective outcomes such as improvement in quality of life, perceived needs for care and dissatisfaction with services showed the strongest associations with reduction in depressive symptoms. R eduction in positive symptoms was associated with decreased likelihood of p arasuicide. Results did not differ according to diagnostic category. Conclusion. The findings suggest that changes in distinct psychopathologica l dimensions independently and differentially influence outcome. Therapeuti c interventions aimed at reducing symptoms of more than one dimension are l ikely to have more widespread effects.