The EQ-5D-5L in amyotrophic lateral sclerosis: an international longitudinal exploration as part of ALS-CarE.

BACKGROUND: The EuroQol 5-Dimension 5-Level questionnaire (EQ-5D-5L) is widely used in health outcomes research, but its longitudinal performance in amyotrophic lateral sclerosis (ALS), particularly across international cohorts, remains poorly characterized. This study examined whether the EQ-5D-5L captures clinically meaningful change over time in ALS and how national value sets influence interpretation of that change. METHODS: EQ-5D-5L data from 296 patients across six European ALS centers in five countries were analyzed over 18.6 months (IQR 17.9-20.8). Baseline and follow-up assessments were compared using the Paretian Classification of Health Change and Health Profile Grids. Country-specific tariffs were applied to identical health-state transitions. Associations between EQ-5D measures and King's stage were assessed. RESULTS: Overall health states worsened over time, although mixed change remained common (31.0%-39.0%), reflecting simultaneous improvement and deterioration across dimensions. Pain/discomfort and anxiety/depression were the only domains showing notable improvement at later follow-up. Mean health-state ranks worsened from 619.65 at baseline to 857.20 at follow-up. However, the apparent magnitude of progression differed substantially according to national tariff selection, with pooled mean utility change ranging from -0.081 under the Dutch tariff to -0.112 under the Italian tariff. Both EQ-5D index and visual analog scale scores correlated with progression according to the King's staging system. CONCLUSIONS: The EQ-5D-5L captures plausible longitudinal deterioration in ALS, but interpretation is strongly influenced by valuation context. National tariffs may materially alter the apparent size of quality-of-life change in multinational ALS studies.