Update on the assessment of children with juvenile idiopathic inflammatory myopathy.

The availability of validated measurement tools to assess children with juvenile idiopathic inflammatory myopathies is critical to clinical care and to ongoing research into new therapeutic modalities and approaches. Recent work has led to the development of tools for assessment of muscle strength and physical function, skin disease, global disease activity and damage, extramuscular disease, and quality of life. Ongoing work is attempting to integrate these assessments into core sets and definitions of improvement and flare. Future work will refine these assessments and definitions and--where there are multiple choices--determine which tools constitute an optimal assessment.