Characteristics of two alternative schizophrenia remission definitions: Relationship to clinical and quality of life outcomes

Abstract

Background The goal of these secondary analyses of clinical trial data was to characterize clinical outcomes in patients with schizophrenia who met symptom severity or duration thresholds for two alternative definitions of remission, and to explore their relationships to improvement duration and quality of life outcomes. Methods Definition 1 used threshold criteria for selected PANSS items sustained over at least 6-months Definition 2 used Brief Psychiatric Rating Scale (BPRS) % change, a threshold score for the Clinical Global Improvement-Severity (CGI-S) maintained for at least 8 weeks, and threshold scores for selected BPRS items. Positive and Negative Symptom Scale (PANSS) and Quality of Life scale (QLS) total scores were pooled from 6 clinical trials. The extent to which the alternative severity thresholds from these two definitions and duration of clinical improvement were associated with different clinical and QLS outcomes was explored. Regression analysis also assessed the relative contribution of each of the components of the two definition severity thresholds to improvements in QLS Total score. Results Increases in QLS scores were greater for those patients who met either threshold criteria relative to those who met neither ( p < .0001). Significantly greater improvements in QLS scores were observed for patients who met either threshold criteria at the 8-, 16- and 24-week visits relative to those who met criteria at weeks 16 and 24, or at week 24 only ( p < 0.001), as well as for the subset of patients who met threshold criteria at both 24 and 52 weeks relative to those who met criteria at only one of these 2 time points. Only 31% to 47% of patients meeting threshold criteria for either definition at the 8-, 16- or 24-week visits remained in remission at the 52-week visit. Among the severity threshold components analyzed, BPRS total % change from baseline was the strongest predictor of improvement in QLS scores. Conclusions Quality of life improved most for patients who achieved severity thresholds associated with either remission criteria and who stayed improved for longer periods. Total BPRS change scores accounted for the greatest percentage of the QLS scores variance. Only a fraction of patients who meet severity criteria for either remission definition early in treatment will remain at that level of improvement within the subsequent 9–12 months.