Symptom rating scales and outcome in schizophrenia

Abstract

Background: Symptom rating scales are now well established in schizophrenia research but their scores are not the same as outcome. Aims: To appraise the usefulness of symptom rating scales in evaluating the outcome of people with schizophrenia. Method: Literature on the use of the Brief Psychiatric Rating Scale (BPRS) the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression (CGI) in schizophrenia research was studied. Results: Scales were designed to make diagnoses, to categorise patients, syndromes or both, and to demonstrate antipsychotic efficacy, as well as to measure outcome. There is much redundancy both between and within scales. Early work suggests limited concurrent validity with external outcome variables. Data are at best ordinal and there are particular difficulties in equating outcome with percentage changes in scores. The concept of remission, which uses absolute item score thresholds with a duration criterion, is a promising outcome measure. Conclusions: Symptom rating scale scores can only comprise a limited part of outcome measurement. Standardised remission criteria may present advantages in outcome research.