Cross-diagnostic validity of the SF-36 physical functioning scale in patients with stroke, multiple sclerosis and amyotrophic lateral sclerosis: A study using Rasch analysis

Abstract

OBJECTIVE: The aim of this study was to investigate unidimensionality and differential item functioning of the SF-36 physical functioning scale (PF10) in patients with various neurological disorders. PATIENTS: PATIENTS post-stroke (n = 198), with multiple sclerosis (n = 151) and amyotrophic lateral sclerosis (n = 193) participated. METHODS: Unidimensionality of the PF10 within the patient groups was investigated by performing a separate Rasch analysis for each group. Differential item functioning was investigated in a pooled Rasch analysis of the 3 groups. RESULTS: Within each group, all items fitted the Rasch model, except the "bathing/dressing" item in the amyotrophic lateral sclerosis gro..