Inter-rater and intra-rater reliability of an adapted Wolf motor function test for older patients with shoulder injuries

The Wolf motor function test (WMFT) evaluates the upper extremity performance of patients with neurological disorders and traumatic brain injuries by assessing time and functional capacity. It was later modified to also measure the quality of the performed movements. This study aimed to adapt the WMFT for patients with shoulder injuries and to evaluate the inter-rater and intra-rater reliability of this adapted version. A total of 20 individuals with a median age of 80.5 years were assessed using a test-retest design after surgical or conservative treatment of shoulder injuries. Two raters rated performance to determine inter-rater reliability. One rater rated the performance again to determine intra-rater reliability. Both inter-rater and intra-rater agreement were determined by weighted Cohen's kappa statistics with corresponding confidence intervals. Cronbach's alpha was calculated to determine internal consistency. The inter-rater Cohen's kappa values ranged from 0.84-1.00 for functional capacity and from 0.79-1.00 for quality of movement. For intra-rater reliability the Cohen's kappa ranged from 0.71-1.00. Cronbach's alpha was > 0.94 for functional capacity and > 0.96 for quality of movement. The adapted version of the WMFT shows high intra-rater and inter-rater reliability for patients with shoulder injuries.