Health-Related Quality of Life in Patients with Spinocerebellar Ataxia: a Validation Study of the EQ-5D-3L
Authors: Buchholz Maresa , Weber Niklas , Rädke Anika , Faber Jennifer , Schmitz-Hübsch Tanja , Jacobi Heike , Xie Feng , Klockgether Thomas , Michalowsky Bernhard ,   The EUROSCA study group, du Montcel Sophie Tezenas , Bauer Peter , Giunti Paola , Cook Arron , Labrum Robyn , Parkinson Michael H. , Durr Alexandra , Brice Alexis , Charles Perrine , Marelli Cecilia , Mariotti Caterina , Nanetti Lorenzo , Panzeri Marta , Rakowicz Maria , Sulek Anna , Sobanska Anna , Schöls Ludger , Hengel Holger , Baliko Laszlo , Melegh Bela , Filla Alessandro , Antenora Antonella , Infante Jon , Berciano José , van de Warrenburg Bart P. , Timmann Dagmar , Szymanski Sandra , Boesch Sylvia , Kang Jun-Suk , Pandolfo Massimo , Schulz Jörg B. , Molho Sonia , Diallo Alhassane ,   The ESMI study group, Hübener-Schmid Jeanette , Santana Magda , Grobe-Einsler Marcus , Koyak Berkan , Raposo Mafalda , Lima Manuela , Garcia-Moreno Hector , Giunti Paola , de Almeida Luís Pereira , van de Warrenburg Bart , van Gaalen Judith , Timmann Dagmar , Thieme Andreas , Reetz Kathrin , Dogan Imis , Wilke Carlo , Schöls Ludger , Riess Olaf , Synofzik Matthis , de Vries Jeroen , Infante Jon , Gulin Oz , Joers James , Onyike Chiadikaobi , Povazan Michal , Ratai Eva-Maria , Schmahmann Jeremy 
Published: September 2023

Although health-related quality of life (HRQoL) has developed into a crucial outcome parameter in clinical research, evidence of the EQ-5D-3L validation performance is lacking in patients with spinocerebellar ataxia (SCA) types 1, 2, 3, and 6. The objective of this study is to assess the acceptability, validity, reliability, and responsiveness of the EQ-5D-3L. For n = 842 predominantly European SCA patients of two longitudinal cohort studies, the EQ-5D-3L, PHQ-9 (Patient Health Questionnaire), and ataxia-specific clinical assessments (SARA: Scale for Assessment and Rating of Ataxia; ADL: activities of daily living as part of Friedreich’s Ataxia Rating Scale; INAS: Inventory of Non-Ataxia Signs) were assessed at baseline and multiple annual follow-ups. The EQ-5D-3L was evaluated regarding acceptability, distribution properties, convergent and known-groups validity, test-retest reliability, and effect size measures to analyze health changes. The non-item response was low (EQ-5D-3L index: 0.8%; EQ-VAS: 3.4%). Ceiling effects occurred in 9.9% (EQ-5D-3L) and 3.0% (EQ-VAS) with a mean EQ-5D-3L index of 0.65 ± 0.21. In total, convergent validity showed moderate to strong Spearman’s rho (rs > 0.3) coefficients comparing EQ-5D-3L and EQ-VAS with PHQ-9, SARA, ADL, and INAS. EQ-5D-3L could discriminate between groups of age, SARA, ADL, and INAS. Intra-class correlation coefficients (EQ-5D-3LICC: 0.95/EQ-VASICC: 0.88) and Kappa statistics (range 0.44 to 0.93 for EQ-5D-3L items) indicated tolerable reliability. EQ-5D-3L shows small (effect size < 0.3) to moderate (effect size 0.3–0.59) health changes regarding ataxia severity. The analysis confirms an acceptable, reliable, valid, and responsive recommended EQ-5D-3L in SCA patients, measuring the HRQoL adequately, besides well-established clinical instruments.