How Valid and Responsive Are Generic Health Status Measures, such as EQ-5D and SF-36, in Schizophrenia? A Systematic Review

OBJECTIVES: Generic health status measures such as the short form health survey (SF-36) and EuroQol-5D (EQ-5D) are increasingly being used to inform health policy. They are claimed to be applicable across disease areas and have started to be used within mental health research. This review aims to assess the construct validity and responsiveness of four generic health status measures in schizophrenia, including the preference-based SF-6D and EQ-5D. METHOD: A systematic review of the literature was undertaken. Ten databases were searched from inception to August 2009 and reference lists scrutinized to identify relevant studies. Studies were appraised and data extracted. A narrative synthesis was performed of the evidence on construct validity including known groups validity (detecting a difference in health-related quality of life (HRQL) scores between two different groups such as samples from the general population and people with schizophrenia), convergent validity (strength of association between generic HRQL and other measures (e.g., symptom or functional), and responsiveness. Responsiveness was considered by: 1) differences in generic HRQL measure scores in responders/non-responders and 2) correlation between changes on generic HRQL measures and changes in specific measures obtained from patients and clinicians. RESULTS: Thirty-three studies were identified that provided data on the validity and/or responsiveness of the instruments. Most of the evidence concerns the SF-36 and EQ-5D, and for these instruments there was evidence for known group validity. The evidence for convergent validity and responsiveness was mixed, with studies presenting contradictory results. CONCLUSION: Although the evidence base is limited in a number of important respects, including problems with the measures used to develop constructs in the validation studies, it is sufficient to raise doubts about the use of generic measures of health like the EQ-5D and SF-36 in patients with schizophrenia.