The value of EQ-5D-3L and EQ VAS as a patient-reported outcome measure for patients with ankylosing spondylitis in routine healthcare: an evaluation of construct validity and responsiveness based on the Swedish Rheumatology Quality Register
摘要
EQ-5D-3L is a generic health-related quality of life (HRQoL) instrument, widely used in both economic and non-economic research. The purpose of this study is to examine the construct validity and responsiveness of EQ-5D-3L (descriptive system and EQ-5D-3L index), as well as EQ VAS in patients with ankylosing spondylitis (AS).
MethodologyThe study is based on real-world individual-level data from the Swedish Rheumatology Quality Register. To assess construct validity and responsiveness, we formulated and tested hypotheses concerning expected correlations between EQ-5D-3L and EQ VAS scores and those of comparator instruments (Bath Ankylosing Spondylitis Disease Activity Index, Ankylosing Spondylitis Disease Activity Score, Bath Ankylosing Spondylitis Functional Index, visual analogue scale for pain, fatigue, and general health), as well as expected differences between patient groups stratified by disease activity or physical function. Further, the area under the receiver operating characteristic curve was analysed. At least 75% of the predetermined hypotheses had to be confirmed to support construct validity or responsiveness.
ResultsIn total, 4,878 patients with AS were included in this study. As expected, the correlations between EQ-5D-3L and EQ VAS scores and those from the comparator instruments were moderate or strong. Further, EQ-5D-3L and EQ VAS were able to detect expected differences between groups. Changes in EQ VAS over time also showed moderate to strong correlations with corresponding changes in comparator instruments. However, the changes in the EQ-5D-3L dimensions self-care and usual activities had weaker correlations than expected with changes in the comparator instruments.
ConclusionOver 75% of the hypotheses for construct validity of EQ-5D-3L and EQ VAS were confirmed, supporting their construct validity in patients with AS. Responsiveness of EQ VAS was also supported. However, limited responsiveness of the dimensions in the EQ-5D-3L indicates that the descriptive system and the EQ-5D-3L index may not fully capture changes over time among patients with AS.