Intra-rater and inter-rater reliability of the 10-point Manual Muscle Test (MMT) of strength in children with juvenile idiopathic inflammatory myopathies (JIIM)

Abstract

Objective: Children with juvenile idiopathic inflammatory myopathies (JIIM) present with muscle inflammation and decreased strength that may affect their functional abilities. The purpose of this study was to determine the intra-rater and inter-rater reliability of the 0 to 10-point manual muscle testing method for children with JIIM.

Methods: For the intra-rater and inter-rater reliability studies, 10 and 9 children with JIIM participated, respectively. For intra-rater reliability, one pediatric therapist completed two assessments in one day with a one-hour break. For inter-rater reliability, four therapists assessed the same child within a single morning.

Results: Spearman correlations for intra-rater reliability ranged from 0.70 to 1.00. Kendall's W coefficient for inter-rater reliability of groups of muscles (total, proximal, distal, and peripheral) ranged from 0.51 to 0.76.

Conclusions: The total, proximal, and peripheral Manual Muscle Test (MMT) score, using the 0-10 point scale, has acceptable reliability in JIIM patients.