Reliability, validity and ability to detect change of the Personal and Social Performance scale in patients with stable schizophrenia

This report describes the measurement properties of the Personal and Social Performance scale (PSP), a clinician-reported measure of severity of personal and social dysfunction, in an outpatient population with stabilized schizophrenia. Pooled data from two similar antipsychotic clinical studies were analyzed (n=411). The PSP showed good test-retest reliability (intraclass correlation coefficient = 0.79). The PSP was more highly correlated with the Strauss-Carpenter Level of Function, an instrument measuring a similar construct, than the Positive and Negative Syndrome Scale, an instrument measuring a different construct. There was a statistically significant difference between mean PSP scores in subjects grouped by their severity rating on the Clinical Global Impression-Severity (CGI-S) (mild or less versus at least moderate), indicating the ability to discriminate between known groups. Effect sizes for mean change in the PSP based on I-category improvement (0.72) or worsening (-0.88) versus no change in the CGI-S were moderate to large, demonstrating the ability to detect change. Estimates of between-group minimum important difference suggest that a 7-point improvement in the PSP may be clinically meaningful in a clinical trial setting. Initial reliability and validity assessments suggest the PSP may be a useful measure of social functioning in patients with stable schizophrenia. (c) 2007 Elsevier Ireland Ltd. All rights reserved.