Psychometric properties of the EQ-5D in rare ataxia diseases (EQ-5D-ATAX)


Project overview

Duration:09/2021 – 03/2023
Project lead:Dr. Bernhard Michalowsky
Project type:Validation study, Joint project
Project funding:Third party funded
Funded by:EuroQol Research Foundation


Spinocerebellar ataxia (SCA) and Friedreich ataxia (FA) are rare (2-4 cases per 100.000 people) autosomal, inherent, and neurodegenerative diseases, characterized by muscle weakness, sensory loss, imbalance, poor coordination, and limited cognitive and mental health. Unfortunately, little is known about these patients' health-related quality of life. Further, evidence about the psychometric performance of health-related quality of life measures, like the EQ-5D, is currently lacking.

The project objective

The study aims to assess the psychometric properties of the EQ-5D-3L (acceptability, validity, health change/responsiveness) in patients with rare ataxia disorders (SCA and FA).

Data basis

The analysis will be based on data from three prospective, longitudinal observational ataxia cohort studies conducted at up to 17 European study centres. The EQ-5D-3L was used in all studies. The EFACTS study (European Friedreich Ataxia Registry) was initiated in 2010 at eleven study centres in Europe and surveyed patients with Friedreich's ataxia about their quality of life over several years. In the ESMI study (European Spinocerebellar Ataxia Type 3/Machado-Joseph Disease Initiative), patients with spinocerebellar ataxia type 3 (SCA 3) were recruited and questioned about their health over a follow-up period of several years. The third data set is the SCA Registry (Registry for Spinocerebellar Ataxies (SCA)), in which patients with spinocerebellar ataxia types 1, 2, 3 and 6 were included and interviewed at multiple time points.


For the first time, the project evaluates a large sample of patients with rare ataxia diseases about their health-related quality of life. We use typical statistical parameters of the classical test theory to examine the EQ-5D-3L's applicability,  reliability, validity, and responsiveness in this cohort. In addition to clinical parameters (e.g. assessing ataxia severity), our study will support the inclusion of the patient's subjective health state in clinical trials and economic evaluation studies.

Participating institutions

McMaster University, Department Health Research Methods, Evidence and Impact, Hamilton, Canada.


PD Dr. Dr. Bernhard Michalowsky
Group Leader within the Career Development Fellow Program
+49 3834 86-8530

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