Comparing disease-specific and generic quality of life measures in patients with schizophrenia.

The current study aimed to compare the use of a disease-specific and a generic quality of life (QOL) measure in a group 251 outpatients with a schizophrenia spectrum disorder by examining their relationships with symptoms of schizophrenia, psychiatric and medical comorbidities, and other factors, as well as to determine which of these factors will be associated with the measurement discrepancy between the two measures. QOL was assessed with the generic Healthy Utility Index Mark 3 (HUI3) and disease-specific Schizophrenia Quality of Life Scale (SQLS), and symptom severity was determined using the Positive and Negative Syndrome Scale (PANSS). Symptom severity predicted both SQLS and HUI3, while psychiatric comorbidity predicted only the HUI3. Ethnicity, employment and PANSS depression factor were significantly associated with the measurement discrepancy. Using domain scores of the two QOL measures, the HUI3 appears to be superior in discriminating PANSS cognitive factor scores and medical comorbidity status compared to SQLS. Although the use of disease-specific QOL is generally preferred to track treatment progress in clinical settings, the two types of instruments measure non-overlapping aspects of QOL and the generic scales may better reflect QOL impairment due to overall clinical presentation.