Responsiveness of the EuroQoL 5-dimension (EQ-5D) in adolescent idiopathic scoliosis

Abstract

Purpose: To test the responsiveness of the EuroQoL 5-dimension (EQ-5D) utility scores for adolescent idiopathic scoliosis (AIS). Methods:A baseline sample of 227 AIS patients was recruited between August and October 2015, and was surveyed prospectively to 9–12 months follow-up. EQ-5D-5L utility scores were derived using a two-step approach: (1) cross-walking from five-level responses to three-level responses and (2) applying the EQ-5D-3L Chinese population value set. An anchor approach was adopted to assess the responsiveness of EQ-5D. Effect size statistics (standardized effect size and standardized response mean) and independent t test were used to assess the responsiveness, as well as to analyze the ability of measures to detect score changes with global health condition changes or discriminate between the worsened and unchanged/improved groups. Results: Approximately two-thirds of follow-up patients (64.2%) reported no change in global health condition based on the self-reported health anchor, whilst 4.6 and 31.3% of patients rated worse and better in current health condition compared to baseline, respectively. In the subgroup where health worsened, EQ-5D utility scores were responsive to detect negative changes. EQ-5D utility scores had slight improvement in the group where health improved, despite a high mean score of 0.92 at baseline. Neither statistical significance nor moderate–large effect size was observed in mean changes among unchanged group. Responsiveness property of the EQ-5D utility score was generally satisfactory with respect to each health condition group. Conclusions: EQ-5D is found to be able to capture positive changes, and responsive in detecting important clinical changes in the improved group of this AIS population.