Rasch analysis of the Unidimensional Self‐Efficacy Scale in Neuromuscular Disorders and comparison between sex, age, and diagnoses

Abstract

AbstractIntroduction/AimsSelf‐efficacy reflects a person's perceptions of their capabilities for specific tasks and influences motivation and performance. The Unidimensional Self‐Efficacy in Neuromuscular Disorders (USE‐NM) was modified from the Multiple Sclerosis (MS) USE‐MS scale and administered to patients attending a specialist neuromuscular clinic. The aim was to investigate this measure in neuromuscular disorders and to compare between patient sex, age, and diagnosis.MethodsThe USE‐NM was posted to patients recruited from a specialist neuromuscular clinic at the Walton Centre. Responses were subjected to Rasch analysis using RUMM2030 software and descriptive statistics were performed using SPSS version 28.ResultsOne hundred and ninety‐eight patients (56.1% male) grouped by age (<50; 50–59; 60–69; and >69 years) and with varied NM disorders returned the USE‐NM. It did not meet the Rasch model expectations due to disordered thresholds of items 6 and 8 (“Sometimes I feel inadequate as a person because of my neuromuscular disorder” and “I feel that my social life would be better if I did not have a neuromuscular disorder”). Following item re‐scoring, the modified USE‐NM satisfied the Rasch model with a unidimensional scale free from differential item functioning and an overall chi‐square probability of 0.146 with good reliability and validity. Post hoc nonparametric testing showed no significant difference in fatigue between sex, age, and neuromuscular diagnoses.DiscussionThe Rasch‐modified USE‐NM offers a measure of self‐efficacy for neuromuscular disorders encountered in a typical specialist clinic. Future considerations could be given to assessing any benefits of multidisciplinary team input, across a specialist neuromuscular service.