EQ-5D vs SF-6D: Discrepancies in measuring quality of life for patients with vertebral compression fractures.

Introduction: EuroQoL-5D (EQ-5D) and SF-6D are both designed to measure health states or utility but differ in questionnaire structure and scoring algorithm. This yields divergent results in several populations. The magnitude of this discrepancy in patients with osteoporotic vertebral compression fractures (OVCF) is unknown. Research question: To compare EQ-5D and SF-6D in determining health states and utility in patients with OVCF. Materials and methods: Registry EQ-5D and SF-6D from patients treated for OVCF with vertebroplasty at a single center were obtained for a preoperative cross-sectional analysis. Response distributions were evaluated for boundary effects. Discrepancies between utility scores were assessed by Wilcoxon signed rank tests, intraclass correlation coefficients and Bland-Altman plots. Results: The analysis included 736 patients. The most frequent response was the floor level in a single EQ-5D dimension and in half of SF-6D dimensions. SF-6D utility median was 0.50 (range 0.30 to 0.91) and EQ-5D utility scores were bimodal with median 0.16 (range -0.594 to 1). Median difference (SF - EQ) was 0.34 (range -0.51 to 1.08). Inter-rater agreement was poor: ICC = 0.158 (CI -0.019; 0.314). Discussion and conclusion: EQ-5D and SF-6D are not interchangeable for patients with OVCF undergoing vertebroplasty. Median differences are large, and SF-6D produces systematically higher utility scores than EQ-5D in patients with poor health while the reverse is true for good health. Differing scoring algorithms and more floor effects in SF-6D than EQ-5D may contribute to utility discrepancy.Researchers are urged to be mindful of this discrepancy when interpreting health states and utility.