Functional Rating Scales in Spinal and Bulbar Muscular Atrophy: A Systematic Review, Meta-Analysis and Critical Appraisal of their Measurement Properties

Tracking disease progression and treatment effect of spinal bulbar muscular atrophy, or Kennedy9s disease, is challenging given its slowly progressive nature. To achieve success in SBMA clinical trials, a reliable, responsive, and validated patient-reported motor function scale must capture progression of SBMA-specific motor dysfunction. Here, we conducted a systematic review, meta-analysis, and appraisal of core measurement properties of the SBMA functional rating scale (SBMAFRS). We established that the SBMAFRS has satisfactory internal consistency, inter-rater reliability, and construct validity for measuring progressive motor dysfunction over similar neurodegenerative motor function scales but inadequate sensitivity to change over time. Further development to validate and improve the SBMAFRS9 ability to capture longitudinal responsiveness in larger cohorts is warranted.