Detecting improvement in quality of life and symptomatology in schizophrenia

Instrument-based scores are often used as outcome measures. However, little is known about what changes in scores mean in terms of a clinical assessme nt of improvement or deterioration. The purpose of this report was to deter mine how much change in standard instrument scores represents a clinically detectable improvement or deterioration. The Veterans Affairs (VA) Cooperat ive Study of Clozapine in Refractory Schizophrenia evaluated 423 patients o n clozapine or haloperidol. Symptoms and quality of life scales were comple ted at baseline; 6 weeks; and 3, 6, and 12 months. Among patients judged as "improved" by clinicians, the average percentage changes were a 21 percent decrease in Positive and Negative Syndrome Scale (PANSS) scores and a 26 p ercent increase in Quality of Life Scale (QLS) scores across all followup p eriods. The change in mean seven-point item scores were -0.46 (PANSS) and 0 .23 (QLS). A major gain in clinically assessed improvement to "much better" was associated with a 45 percent decline in PANSS scores and 50 percent in crease in QLS scores (change in mean seven-point item scores -0.88 and 0.92 , respectively). Thus, modest changes in psychometric scales assessing symp toms and quality of life reflect clinically detectable improvement.