Objective: The objective was to validate the well-established EQ-5D in Friedreich’s ataxia (FA).

Background: Health-related quality of life (HRQoL) is increasingly researched in FA. The high need for care and the tremendous psychosocial and economic burden for these predominantly young patients makes it necessary to focus on HRQoL and validate commonly used generic patient-reported outcome measures.

Method: The analysis was based on data from 463 FA patients of the observational EFACTS cohort study carried out at eleven clinical study centres in seven European countries. FA patients annually completed the following HRQoL and clinical questionnaires from baseline to four-year follow-up: the EQ-5D-3L and EQ-VAS, the Scale for Assessment and Rating of Ataxia (SARA), the Inventory of Non-Ataxia Signs (INAS), and the Activities of Daily Living (ADL) part of FA rating scale. EQ-5D-3L utility indices were calculated using the European value set. The EQ-5D-3L and the EQ-VAS were evaluated in terms of distribution properties (score ranges, floor and ceiling effects, known-groups validity, convergent validity (Spearman correlation coefficients, rs), and responsiveness (standardized effect sizes (SES), response mean (SRM).

Results: Most patients had high ataxia severity (mean SARA=21.9; SD=9.64) with a mean health utility of 0.58 (SD=0.21). The EQ-5D-3L utilities ranged from 0.07 to 1.0, with a ceiling effect of 2.4%. The EQ-5D-3L satisfies known-groups validity by significantly differentiating between stages of age, ataxia severity (SARA), limitations of ADL and number of non-ataxia symptoms (INAS). EQ-5D-3L utility showed moderate to strong correlations with SARA (rs=-0.680), INAS (rs=-0.482) and ADL (rs=-0.713), revealing a satisfactory convergent validity. The EQ-5D-3L showed moderate responsiveness to detect health changes (SES:0.34, SRM:0.42). EQ-VAS poorly correlated with SARA (rs=-0.098), INAS (rs=-0.017) and ADL (rs=-0.100) and was not responsive to health changes (SES:0.11, SRM:0.085).

Conclusion: The psychometric analyses demonstrated a satisfactory validity of the EQ-5D-3L in patients with FA and show that the HRQoL reflects the patient’s disease stages. The EQ-5D-3L index could adequately measure HRQoL in FA and is a suitable parameter besides well-established clinical instruments. However, further research is needed to understand the low responsiveness of the EQ-5D and evaluate the differences in the psychometric performance of the EQ-VAS in FA.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/validity-and-responsiveness-of-the-eq-5d-3l-in-friedreich-ataxia/