Validity and responsiveness of the EQ-5D in assessing and valuing health status in patients with anxiety disorders

Abstract

Background: The EQ-5D is a generic questionnaire which generates a health profile as well as index scores for health-related quality of life that may be used in cost-utility analysis.

Aims of the study: To examine validity and responsiveness of the EQ-5D in patients with anxiety disorders.

Methods: 389 patients with anxiety disorders completed the EQ-5D at baseline and 6-month follow-up. Subjective measures of quality of life (WHOQOL-BREF) and psychopathology (BAI, BDI-II, BSQ, ACQ, MI) were used for comparison. Validity was analyzed by assessing associations between EQ-5D scores and related other scores. Responsiveness was analyzed by calculating effect sizes of differences in scores between baseline and follow-up for 3 groups indicating more, constant or less anxiety. Meaningful difference scores for shifting to less or more anxiety were derived by means of regression analysis.

Results: 88.4% of respondents reported problems in at least one of the EQ-5D dimension at baseline; the mean EQ VAS score was 63.8. The EQ-5D dimension most consistently associated with the measures used for comparison was 'anxiety/depression'. EQ VAS and EQ-5D index scores were highly correlated (|r|>0.5) with scores of the WHOQOL-BREF dimensions 'physical', 'mental' and 'overall' as well as BAI and BDI-II. The EQ-5D index tended to be the most responsive score. Standardized meaningful difference scores were not significantly different between EQ VAS, EQ-5D index and measures used for comparison.

Conclusions: The EQ-5D seems to be reasonably valid and moderately responsive in patients with anxiety disorders. The EQ-5D index may be suitable for calculating QALYs in economic evaluation of health care interventions for patients with anxiety disorders.

Trial registration: Current Controlled Trials ISRCTN15716049.

Figure 1

Distribution of responses to items of EQ-5D descriptive system in patient sample (n = 389) and general population (n = 3552) [40]. In the patient sample there were 7 missing values for the EQ-5D items 'mobility', 'self-care', 'usual activities', 10 missing values for the item 'pain/discomfort' and 8 missing values for the item 'anxiety/depression'.