Background. The effectiveness of therapeutic interventions in psychosis is increasingly reported in
terms of reductions in different symptom dimensions. 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 assessed on three occasions
over 2 years (baseline, year 1 and year 2). A multilevel analysis was conducted to examine to what
degree reduction in psychopathological scores derived from factor analysis of the Comprehensive
Psychopathological 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 over the study period were
all independently associated with lessening of social disability. Reduction in negative symptoms,
and to a lesser extent in positive and manic symptoms, was associated with less time in hospital and
more time living independently, whereas changes in positive and manic symptoms 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. Reduction in positive symptoms was associated with decreased likelihood of parasuicide.
Results did not differ according to diagnostic category.
Conclusion. The findings suggest that changes in distinct psychopathological dimensions
independently and differentially influence outcome. Therapeutic interventions aimed at reducing
symptoms of more than one dimension are likely to have more widespread effects.