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

## TL;DR

This study compares two versions of a rating scale for ALS patients and finds they can be used interchangeably with high agreement.

## Contribution

The study demonstrates that the self-explanatory version of the ALSFRS-R can be used reliably in clinical settings.

## Key findings

- Total scores from both versions of the ALSFRS-R showed high correlation and concordance.
- Item-level agreement was high on average, with some variability in specific items.
- The self-explanatory version was robust across remote and paper-based assessments.

## Abstract

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.

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.

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.

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.