The main purpose of this study was to assess the construct validity of the Greek EQ-5D instrument in measuring health-related quality of life, as well as to address the issues of concurrent validity, internal consistency reliability, and sensitivity.
A stratified, representative sample (n = 1388) of the Greek general population was approached for interview (response rate 72.4%). The survey included the EQ-5D, the SF-36, and questions on sociodemographic and clinical characteristics of the sample.
The EQ-5D dimensions, the EQ visual analog scale, and the UK-based utility index were capable of distinguishing between groups of respondents, in the expected manner, on the basis of sex, age, education, socioeconomic status, self-reported health problems, and health services utilization, thus providing evidence of construct validity. Convergent and divergent validity of the EQ-5D descriptive system were supported by expected relationships with SF-36 scale and summary scores. Additionally, reporting a problem in a given EQ dimension was generally associated with lower SF-36 scores, supporting concurrent validity. Internal consistency reliability and sensitivity were also satisfactorily demonstrated.
The results provide initial support for the construct validity of the EQ-5D in Greece, and, in conjunction to future studies addressing test–retest reliability and responsiveness, they support administering the instrument in health status studies, which in turn can contribute to transnational comparisons.