Variability across versions of the self-administered ALSFRS-R: a review and call for harmonization

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease predominantly affecting motor neurons resulting in substantial, progressive disability. The amyotrophic lateral sclerosis functional rating scale - revised (ALSFRS-R) is commonly used to assess and monitor functional status in patients with ALS. Additionally, it is the current regulatory accepted primary outcome measure documenting functional status in ALS clinical trials. The ALSFRS-R was originally designed to be administered to a patient by a trained professional. But over time it has been adapted to be performed independently by patients or their caregivers without assistance. Several different versions of the self-administered ALSFRS-R have been created over the past two decades, each with subtle but important differences. Some of these differences are related to language used in item wording or the platform for which the scale was intended to be administered (e.g. digitally). These differences across versions of the self-administered scale may be problematic as they could increase the heterogeneity of data collected across clinical trials or complicate interpretation of results across trials. Therefore, we highlight the need for a harmonized version of the self-administered ALSFRS-R to be used across all clinics and clinical trial sites internationally.