Construct Validity of the Amyotrophic Lateral Sclerosis Bulbar Dysfunction Index-Remote

The Amyotrophic Lateral Sclerosis Bulbar Dysfunction Index-Remote (ALSBDI-R) is a clinician-administered tool designed to assess bulbar dysfunction remotely in patients with amyotrophic lateral sclerosis (ALS). This study aimed to evaluate the construct validity of the ALSBDI-R by examining its correlation with established clinical measures and its ability to discriminate among different bulbar disease severities.

A total of 92 patients with ALS were recruited from two multidisciplinary clinics. Participants were assessed using the ALSBDI-R, the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R), the Center for Neurologic Study Bulbar Function Scale (CNS-BFS), the Sentence Intelligibility Test, and the Eating Assessment Tool (EAT-10). Construct validity was established through Spearman correlations and comparison of ALSBDI-R scores across bulbar severity groups (asymptomatic, mild, moderate, severe).

Strong correlations were found between ALSBDI-R total scores and bulbar-specific measures such as ALSFRS-R bulbar subscore (r = -.85), CNS-BFS (r = .85), and EAT-10 (r = .77). The ALSBDI-R effectively discriminated between severity groups, supporting its construct validity. Severity bins were created based on median ALSBDI-R total scores for each group.

The ALSBDI-R is a valid tool for remotely assessing bulbar dysfunction in patients with ALS. Despite several limitations, its ability to capture varying degrees of severity makes it valuable for clinical use and research, offering a standardized approach to monitor disease progression remotely.