Assessing the Measurement Properties of the Self-Administered Amyotrophic Lateral Sclerosis Functional Rating...

Area of Science:

• Neurology
• Biostatistics
• Clinical Assessment

Background:

• The self-administered Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) is crucial for tracking disease progression in individuals with ALS.
• Previous assessments have not utilized Rasch Measurement Theory to evaluate the psychometric properties of the self-administered ALSFRS-R.

Purpose of the Study:

• To examine the psychometric properties of the self-administered ALSFRS-R using Rasch analysis.
• To assess the scale's fit, targeting, dependency, unidimensionality, reliability, and stability.

Main Methods:

• Rasch analysis was conducted on self-administered ALSFRS-R data from 122 individuals with ALS across Canada.
• RUMM2030 software was used to evaluate fit, targeting, dependency, unidimensionality, reliability, and stability, including differential item functioning for sex, age, and language.

Main Results:

• The overall ALSFRS-R showed good fit, reliability, and stability, but revealed multidimensionality.
• Subscale analysis (bulbar, motor, respiratory) demonstrated good fit, reliability, stability, and unidimensionality.
• Item dependency and targeting issues persisted in the subscales.

Conclusions:

• The self-administered ALSFRS-R is reliable, internally valid, and stable across demographic subgroups.
• Scoring the ALSFRS-R by subscale is recommended for clinical use.
• Future research should focus on item revision to address misfit and ceiling effects.