Differential Psychometric Properties of EuroQoL 5-Dimension 5-Level and Short-Form 6-Dimension Utility Measures in Low Back Pain

Abstract

Study Design. Prospective study. Objective. To examine the acceptability, validity, and reliability of EuroQoL 5-dimension 5-level (EQ-5D-5L) and Short-Form 6-Dimension (SF-6D) health utility measures in patients with low back pain (LBP). Summary of Background Data. LBP requires multiple diagnostic tests and treatment that can incur high medical costs. It is thus desirable to have an appropriate measure for cost-utility analysis of various LBP-related interventions. Methods. Health-related quality of life (HRQoL) questionnaires including generic 12-item Short Form Health Survey (SF-12), EQ-5D-5L, and low back/back-related questionnaires were administered at a specialty clinic. SF-12 items responses were transformed to SF-6D utility scores using the Hong Kong population scoring algorithm whereas EQ-5D-5L responses were mapped onto EQ-5D-3L response, then converted to EQ-5D-5L utility scores using the Chinese-specific value set. Construct validity was determined by evaluating Spearman correlation between SF-12 and EQ-5D-5L scores. Correlation between back-specific questionnaires and HRQoL scores were assessed. Results. A total of 100 patients were recruited. No significant (>15%) floor and ceiling effects were observed for EQ-5D-5L and SF-6D scores. Detailed proportion of respondents for each EQ-5D-5L domain indicated that Pain/Discomfort domain was the most prevalent problem. SF-6D utility score and EQ-5D-5L had respective strong (0.600–0.855) and moderate-to-strong (0.455–0.700) correlations with SF-12 domain and summary scores. EQ-5D-5L and SF-6D scores were correlated (0.625), with adequate construct validity as both utility scores conceptually measure the similar construct. Patients with no previous spine surgery nor disc degeneration had significantly higher EQ-5D-5L scores. Both EQ-5D-5L and SF-6D significantly correlated with back-specific questionnaires. Conclusion. Both EQ-5D-5L and SF-6D appeared as applicable and valid measures in assessing HRQoL of LBP patients. Being the first study examining the differential psychometric properties and validation of the use of EQ-5D-5L and SF-6D in Chinese LBP population, this allows future exploration of the impact of utility score selection on assessing effectiveness of clinical intervention for LBP.