Long-term evolution of patient-reported outcome measures in spinocerebellar ataxias

To study the long-term evolution of patient-reported outcome measures (PROMs) in the most common spinocerebellar ataxias (SCAs), we analyzed 8 years follow-up data of the EUROSCA Natural History Study, a cohort study of 526 patients with SCA1, SCA2, SCA3 and SCA6.

To assess the functional capacity in daily living, we used the functional assessment (part IV) of the Unified Huntington's Disease Rating Scale (UHDRS-IV), for health-related quality of life the visual analogue scale of the EuroQol Five Dimensions Questionnaire (EQ-5D VAS), and for depressive symptoms the Patient Health Questionnaire (PHQ-9). Severity of ataxia was assessed using the Scale for the Assessment and Rating of Ataxia (SARA) and neurological symptoms other than ataxia with the Inventory of Non-Ataxia Signs (INAS).

UHDRS-IV [SCA1: - 1.35 (0.12); SCA2: - 1.15 (0.11); SCA3: - 1.16 (0.11); SCA6: - 0.99 (0.12)] and EQ-5D [SCA1: - 2.88 (0.72); SCA2: - 1.97 (0.49); SCA3: - 2.06 (0.55); SCA6: - 1.03 (0.57)] decreased linearly, whereas PHQ-9 increased [SCA1: 0.15 (0.04); SCA2: 0.09 (0.03); SCA3: 0.06 (0.04); SCA6: 0.07 (0.04)] during the observational period. Standard response means (SRMs) of UHDRS-IV (0.473-0.707) and EQ-5D VAS (0.053-0.184) were lower than that of SARA (0.404-0.979). In SCA1, higher SARA scores [- 0.0288 (0.01), p = 0.0251], longer repeat expansions [- 0.0622 (0.02), p = 0.0002] and the presence of cognitive impairment at baseline [- 0.5381 (0.25), p = 0.0365] were associated with faster UHDRS-IV decline. In SCA3, higher INAS counts were associated with a faster UHDRS-IV decline [- 0.05 (0.02), p = 0.0212]. In SCA1, PHQ-9 progression was faster in patients with cognitive impairment [0.14 (0.07); p = 0.0396].

In the common SCAs, PROMs give complementary information to the information provided by neurological scales. This underlines the importance of PROMs as additional outcome measures in future interventional trials.