Objective: To analyze the construct validity of the EQ-5D in patients with acute coronary syndromes (ACS).
Methods: All ACS-diagnosed patients discharged from a university-affiliated hospital during a 3-year period were mailed a questionnaire that included the EQ-5D and the SF-8. The EQ-5D includes a visual analogue scale (EQ VAS) to measure self-reported current health-status (0-100) and a five-item descriptive system measuring mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Also included were disease severity measures [Duke Activity Status Index (DASI), cardiac symptom count (SC), patient-perceived cardiac disease severity], comorbidity measures (Charlson comorbidity index, total medication count), and other demographic and disease-related items.
Results: Of 1217 patients, 490 (40.3%) responded. Patients averaged 65.2 (SD 11.3) years of age; 71.0% male; 91.9% Caucasian; 64.3% history of MI. Only 0.2%-0.4% of EQ-5D items and 8% of the EQ VAS were left unanswered by respondents. The nine most common health states were identified based on the five EQ-5D item scores. Levels of responses to EQ-5D items and the EQ VAS score were significantly better for patients with very mild/mild perceived disease severity compared to severe/very severe, for patients with lower comorbidity, for patients with lower symptom responses, and for patients with a higher cardiac-related functioning. EQ VAS score and SF-8 subscale score correlation coefficients ranged from 0.527 to 0.798 (all p < 0.0001). Significant differences were observed between the response level of individual EQ-5D items and scores of comparable SF-8 subscales.
Conclusions: This study demonstrated the construct validity of the EQ-5D in a population-based sample of patients with a history of ACS.