Open Access

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

• 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.