Clinically meaningful change: evaluation of the Rasch-built Overall Amyotrophic Lateral Sclerosis Disability Scale (ROADS) and the ALSFRS-R

Objective: To investigate clinically meaningful change for ROADS and ALSFRS-R using a patient-defined approach. Methods: Data were reviewed from participants assessed at the Emory ALS Center from 2019-2022 with two assessments using both ROADS and ALSFRS-R and a completed patient-reported global impression of change scale at the second visit. Minimal important difference (MID), or the smallest amount of change that is clinically relevant, was assessed based on patient reported impression of change for ROADS and ALSFRS-R. Minimal detectable change (MDC), the smallest amount of change exceeding the threshold for measurement error, was assessed for ROADS and ALSFRS-R using standard deviations for participants self-rated as "unchanged". Results: Data were included from 162 participants. For ROADS (total possible normed score = 146), MID = 5.81 and MDC = 2.83 points. For ALSFRS-R (total possible sum-score = 48), MID = 3.24 and MDC = 1.59 points. Clinically meaningful decline during the assessment period was observed in 98/162 (60.49%) participants on ROADS and 75/162 (46.30) participants on ALSFRS-R (OR = 1.63, 95% CI [1.0009, 2.66]). Conclusions: Changes that are on average less than 5.81 points (3.98%) on the normed ROADS score or less than 3.24 points (6.75%) on the ALSFRS-R sum-score may not be clinically meaningful according to a patient-defined approach. Understanding the clinical and statistical limitations of these scales is crucial when designing and interpreting ALS research studies.