Introduction: Friedreich Ataxia (FA) is a multisystem neurodegenerative disease. Affected individuals rely on mobility assistive technologies (MAT) (e.g. wheelchairs) and require long-term treatments and care. To analyse the patients' health-related quality of life (HRQoL), the EuroQol 5 Dimension 3 Level survey (EQ-5D-3L)-a widely used and recommended generic measure-is used in clinical and in health economic studies. Concerns about using the instrument in mobility-impaired individuals who might have difficulties finding appropriate response options for mobility-related items led us to investigate how the 3L dimensions perform in patients with FA using or not using MAT.
Methods: Using longitudinal data from 607 patients with FA of the EFACTS study (from baseline to the 3-year follow-up), we analysed the acceptability, distribution properties, validity, and responsiveness of the EQ-5D-3L, focusing on the mobility item. Analyses were stratified for patients without and with different MAT-usage.
Results: We identified that n = 177 patients used no MAT, n = 299 a wheelchair and n = 131 walking aids. The mobility item non-response was highest in wheelchair users (6.8%) and lowest in patients without MAT. Walking aid users showed the least variability, all selecting the mid-response option "some problems" for mobility. The mobility item correlated moderately with disease severity (rsp = 0.35) and the activities of daily living scale (rsp = 0.36) in wheelchair users. No correlation exists for walking aid users. The strongest health changes occurred for wheelchair users, the weakest for walking aid users. The mobility dimensions showed the highest amount of no changes.
Conclusion: The EQ-5D-3L's mobility item has limitations in MAT users, particularly in walking aid users, due to a tendency towards mid-responses. These limitations may affect the efficacy and (cost)effectiveness conclusions drawn from interventions and clinical trials with mobility-impaired individuals. Further research is needed to explore the understanding and interpretation of responses of the EQ-5D in patients with FA with mobility support.
Trial registration: ClinicalTrials.gov identifier NCT02069509.
Keywords: EQ-5D-3L; Friedreich Ataxia; Health-related quality of life; Mobility assistive technology.
Friedreich Ataxia is a rare neurodegenerative multisystem disorder that affects movement and coordination. Many people with Friedreich Ataxia rely on mobility aids like walking sticks or wheelchairs to get around. In studies that measure quality of life, such as with the EQ-5D questionnaire, people with mobility issues often struggle with the questions related to “walking”. This is because the questionnaire does not include options for people using mobility aids, making it difficult for them to answer accurately. Our research found limitations with the EQ-5D-3L’s mobility question in patients with Friedreich Ataxia, using various mobility aids. Many wheelchair users did not answer to the mobility question, while those using walking aids tended to choose the middle option, “some problems”. Poor wording and limited response options could affect the accuracy of health-related quality of life measures, leading to biased conclusions about treatment effectiveness and costs. Therefore, it is essential to rethink how mobility-related questions are structured and formulated to ensure health-related quality of life questionnaires are valid and responsive, particularly for people using mobility aids.
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