Patients with PM/DM (73 children and 45 adults) were assessed at baseline and reevaluated 6-9 months later. We compared Total
MMT (a group of 24 proximal, distal, and axial muscles) and Proximal
MMT (7 proximal muscle groups) tested bilaterally on a 0-10 scale with 144 subsets of 6 and 96 subsets of 8 muscle groups tested unilaterally. Expert consensus was used to rank the best abbreviated
MMT subsets for face validity and ease of assessment.
RESULTS: The Total, Proximal, and best
MMT subsets had excellent internal reliability (Total
MMT r(s) = 0.91-0.98), and consistency (Cronbach's alpha = 0.78-0.97). Inter- and intrarater reliability were acceptable (Kendall's W 0.68-0.76, r(s) = 0.84-0.95).
MMT subset scores correlated highly with Total and Proximal
MMT scores and with the Childhood
Myositis Assessment Scale, and correlated moderately with physician global activity, functional disability, magnetic resonance imaging, and axial and distal
MMT scores, and, in adults, with
creatine kinase level. The standardized response mean for Total
MMT was 0.56 in juveniles and 0.75 in adults. Consensus was reached to use a subset of 8 muscles (neck flexors, deltoids, biceps, wrist extensors, gluteus maximus and medius, quadriceps, and ankle dorsiflexors) that performed as well as the Total and Proximal
MMT, and had good face validity and ease of assessment.
CONCLUSION: