Psychometric validation of the EuroQoL 5-dimension (EQ-5D) questionnaire in patients with spondyloarthritis

Background: Spondyloarthritis (SpA) has a significant impact on patients' quality of life due to functional impairments. Generic health instruments like the EuroQoL 5-dimension (EQ-5D) is important for the cost-utility analysis of health care interventions and calculation of quality-adjusted life years. However, the applicability of the EQ-5D health measure in Chinese patients with SpA is currently unknown. Hence, the aim of the study is to test the psychometric properties and to validate the use of the EQ-5D health measure for utility analyses in Chinese patients with SpA.

Methods: Prospective and consecutive recruitment of 220 Chinese patients with SpA was conducted. Demographic data including smoking and drinking habits, education level, income, and occupation was collected. Disease-associated data including disease duration, the presence of back pain, peripheral arthritis, dactylitis, enthesitis, uveitis, psoriasis, and inflammatory bowel disease was also recorded. Questionnaires regarding disease activity and functional disability (BASDAI, BASFI, BASGI, BASMI, ASDAS, ODI), mental health (HADS depression and anxiety), and the EQ-5D scores were recorded. SF-36 scores were used to verify the findings. Baseline correlations were performed along with test-retest reliability, validity, and internal consistency tests. Specifically, the relationship between EQ-5D and disease activity and functional scores was studied.

Results: EQ-5D scores achieved acceptable internal consistency and reliability. A ceiling effect was observed for all domains of the EQ-5D except for pain/discomfort. No floor effect was observed. Significant negative correlations were observed between ODI, HADS, BASFI, BASMI, BASDAI, and ASDAS-CRP and with EQ-5D. A higher disease activity was well-differentiated by EQ-5D, as with the disability and mental health scores.

Conclusions: The EQ-5D demonstrates satisfactory psychometric properties for assessment of SpA patients. It has high utility for demonstrating changes in disease activity and disability.