Toward the Definition of Patient-Reported Outcome Measurements in Hereditary Spastic Paraplegia

BACKGROUND AND OBJECTIVES: Hereditary spastic paraplegias (HSPs) are a heterogeneous group of rare neurodegenerative diseases, characterized by a progressive spastic paraparesis. Currently, there is a HSP-specific clinician-reported outcome measure (CROM) called Spastic Paraplegia Rating Scale (SPRS). There are, however, no specific patient-reported outcome measures (PROMs) for HSP. In the present cohort study, we prospectively follow up a well-examined Austrian HSP cohort using validated rating scales and compared PROM with disease-specific and non–disease-specific CROM. METHODS: Patients were recruited and followed up at the Center for Rare Movement Disorders, Innsbruck, Austria. CROM included the SPRS, Scale for the Assessment and Rating of Ataxia (SARA), Barthel Index (BI), and Mini-Mental State Examination (MMSE). PROM included the EQ-5D questionnaire and the Patient Health Questionnaire 9 (PHQ-9). Standardized response means (SRMs) were calculated for all scales at follow-up (FU) after 1 year. RESULTS: A total of 55 patients (36 males) with HSP were included in the study. FU was performed for 30 patients (21 males). Apart from females reporting more problems in the EQ-5D domain of anxiety and depression (p = 0.008), other clinician-reported outcomes (CROs) or patient-reported outcomes (PROs) did not differ significantly across sex. SPRS showed significant correlations with SARA (p < 0.001), mainly driven by the gait item, as well as the BI. Although SPRS did not correlate with EQ-5D visual analogue scale and PHQ-9 scores, several EQ-5D domains correlated significantly with SPRS. At FU, SPRS showed the highest responsiveness (SRM 1.11), followed by SARA (SRM 0.47). Neither MMSE nor PRO significantly increased at FU. DISCUSSION: In this study, we present an Austrian cohort of patients with HSP and a prospective study evaluating correlations of CRO and PRO as well as their progression. Demographics from our cohort are comparable with several other European cohort studies. Our data highlight the capabilities of the SPRS to show clinical progression and warrant consideration of ataxia rating scales such as SARA in HSP cohorts. We also show that the generic PROMs are not suitable to detect change in HSP, and thus, we propose to create a disease-specific PROM fully depicting the effect of HSP on the patients' lives.