Development and Testing of Reduced Versions of the Manual Muscle Test-8 in Juvenile Dermatomyositis

To develop and test shortened versions of the Manual Muscle Test-8 (MMT-8) in juvenile dermatomyositis (JDM).Construction of reduced tools was based on a retrospective analysis of individual scores of MMT-8 muscle groups in 3 multinational datasets. The 4 and 6 most frequently impaired muscle groups were included in MMT-4 and MMT-6, respectively. Metrologic properties of reduced tools were assessed by evaluating construct validity, internal...