EQ-5D versus SF-12 in coronary patients: are they interchangeable?
OBJECTIVE
The aim of this study was to compare EuroQol five-dimensional (EQ-5D) utility scores and six-dimensional health state classification (SF-6D) utility scores (derived from the 12-Item Short-Form Health Survey [SF-12]) by using a large European sample of patients with stable coronary heart disease. Special attention was given to country-specific results.


METHODS
Data from the EURopean Action on Secondary and Primary Prevention by Intervention to Reduce Events III (EUROASPIRE III) survey were used. Patients hospitalized for a coronary artery bypass graft, percutaneous coronary intervention, acute myocardial infarction, or myocardial ischemia were interviewed and examined at least 6 months after their acute event. Health-related quality of life was assessed by using the EQ-5D and the SF-12. SF-12 outcomes were converted to SF-6D utility values, allowing comparison between both measures.


RESULTS
Both EQ-5D and SF-6D results were available for 7472 patients with coronary heart disease from 20 European countries. The measures were significantly correlated (intraclass correlation coefficient = 0.536); however, large differences between the two measures remain. A total of 28.8% of the patients reported a ceiling effect on the EQ-5D instrument, whereas only 4.2% of the patients reported full health based on the SF-6D. Especially the mental component does not seem to be completely captured by the EQ-5D instrument. Furthermore, patients with worse EQ-5D outcomes were more likely to have better SF-6D results, whereas patients with better EQ-5D outcomes were more likely to have worse SF-6D results.


CONCLUSIONS
Both measures are not interchangeable. Whereas the main disadvantage of the EQ-5D questionnaire is its ceiling effect, the potential advantages of SF-12 might disappear when converting the outcomes into an SF-6D utility, because of the small differences between patients.
Department of Public Health, Ghent University, Belgium. Electronic address: delphine.desmedt@ugent.be.
Delphine
D
De Smedt
Department of Public Health, Ghent University, Belgium.
Els
E
Clays
Department of Public Health, Ghent University, Belgium; Faculty of Medicine and Pharmacy, Vrije University Brussel, Brussels, Belgium; I-CHER Interuniversity Center for Health Economics, Ghent and Brussels, Belgium.
Lieven
L
Annemans
Department of Public Health, Ghent University, Belgium.
Dirk
D
De Bacquer
D000368:Aged; D000465:Algorithms; D003327:Coronary Disease / Q000453:epidemiology / Q000517:prevention & control* / Q000628:therapy*; D003430:Cross-Sectional Studies; D005060:Europe / Q000453:epidemiology; D005260:Female; D006304:Health Status; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D011322:Primary Prevention; D011788:Quality of Life; D055502:Secondary Prevention; D011795:Surveys and Questionnaires
EQ-5D; SF-12; coronary heart disease; health-related quality of life; utility