Estimating a Minimal Important Difference for the EQ-5D-5L Utility Index in Dialysis Patients

Abstract

ObjectivesThe EQ-5D-5L is a commonly used health-related quality of life instrument for evaluating interventions in patients receiving dialysis; however, the minimal important difference (MID) that constitutes a meaningful treatment effect for this population has not been established. This study aims to estimate the MID for the EQ-5D-5L utility index in dialysis patients. Methods6-monthly EQ-5D-5L measurements were collected from adult dialysis patients between April 2017 and November 2020 at a renal network in Sydney, Australia. EQ-VAS and Integrated Palliative care Outcome Scale Renal symptom burden scores were collected simultaneously and used as anchors. MID estimates for the EQ-5D-5L utility index were derived using anchor-based and distribution-based methods. ResultsA total of 352 patients with ≥1 EQ-5D-5L observation were included, constituting 1127 observations. Mean EQ-5D-5L utility index at baseline was 0.719 (SD ± 0.267), and mean EQ-5D-5L utility decreased over time by −0.017 per year (95% CI −0.029 to −0.006, P = .004). Using cross-sectional anchor-based methods, MID estimates ranged from 0.073 to 0.107. Using longitudinal anchor-based methods, MID for improvement and deterioration ranged from 0.046 to 0.079 and −0.111 to −0.048, respectively. Using receiver operating characteristic curves, MID for improvement and deterioration ranged from 0.037 to 0.122 and −0.074 to −0.063, respectively. MID estimates from distribution-based methods were consistent with anchor-based estimates. ConclusionsAnchor-based and distribution-based approaches provided EQ-5D-5L utility index MID estimates ranging from 0.034 to 0.134. These estimates can inform the target difference or “effect size” for clinical trial design among dialysis populations.