Agreement Between the Harmonized and the Self‐Explanatory Versions of the Revised ALS Functional Rating Scale in a Clinical Setting

Introduction/Aims The harmonized version of the ALS Functional Rating Scale ‐ Revised (ALSFRS‐R) is typically administered according to standard operating procedures (SOPs) to ensure procedural consistency. In contrast, obtaining the self‐explanatory (SE) version of the ALSFRS‐R does not include the use of SOPs. The aim of this study was to examine the level of agreement between the harmonized and the SE version of the ALSFRS‐R in a cohort of ALS patients. Methods In a prospective study, the harmonized ALSFRS‐R was assessed in 107 ALS patients. In parallel, all patients independently completed the ALSFRS‐R‐SE, either on a printed form ( n = 36) or remotely via the ALS App ( n = 71). Agreement between methods was investigated using Spearman's correlation, Lin's concordance correlation coefficient (CCC), Deming regression, Bland–Altman plots and item‐level statistics including Kendall's tau‐b and the Stuart–Maxwell test. Results Total scores from ALSFRS‐R and ALSFRS‐R‐SE showed high correlation ( ρ = 0.91–0.95) and concordance (CCC > 0.9). Deming regression (intercept≈0; slope≈1) and Bland–Altman analysis (95% of values within limits of agreement [LoA]) revealed no systematic bias. Item‐level agreement was high (76.6% on average), with some variability in items such as handwriting, walking, and dyspnea. ALS progression rates were consistent (differences ≤ 0.02). ALSFRS‐R‐SE remained robust across remote digital and paper‐based assessments. Discussion The strong agreement between the harmonized and self‐explanatory versions of the ALSFRS‐R supports their interchangeable use. The SE format may facilitate remote digital assessment and reduce complexity of ALSFRS‐R assessment in research and clinical practice. Further studies are warranted to validate the ALSFRS‐R‐SE across larger cohorts, multiple languages, and diverse rater groups.