Physical activity monitoring: A promising outcome measure in idiopathic inflammatory myopathies.

Abstract

Availability of reliable outcomes for idiopathic inflammatory myopathies (IIM) is critical to optimize treatment strategies.1 The current consensus for the assessment of IIM severity and treatment efficacy relies on the evaluation of core set measures comprising manual muscle testing, muscle enzymes, extramuscular disease activity assessment, physician and patient global disease activity assessment, and patient's physical function questionnaires.2 Muscle enzymes such as serum creatine kinase (CK) level are highly sensitive markers for detecting changes in disease activity though this does not correlate well with disease severity. Manual muscle testing is an operator-dependent and semiquantitative evaluation resulting in poor interrater reliability and poor sensitivity to changes. Disease burden may be imprecisely assessed when using self-reported questionnaires. Floor and ceiling effects associated with these metrics are also of major concern.1,2