Introducing a parent-centred composite disease activity score for remote monitoring in juvenile dermatomyositis

OBJECTIVES: To develop and test a composite disease activity score for juvenile dermatomyositis (JDM) solely based on parent-reported outcomes (PROs). METHODS: The parent JDM Activity Index (ParJDMAI) includes the following four PROs: 1) global assessment of disease activity; 2) assessment of fatigue; 3) assessment of muscle disease activity; 4) assessment of skin disease activity. Each item is weighted on a 0-10 scale, which yields a total score ranging from 0 to 40. Validation procedures were conducted on a multicentre sample of 254 patients with JDM according to the OMERACT filter for outcome measures in rheumatology. RESULTS: The ParJDMAI is short and simple, and is quick, taking < 10 min to complete and score, which makes it practical for use in standard clinical care. In validation analyses, the tool demonstrated good construct validity, satisfactory internal consistency (Cronbach's alpha 0.86) and structure (with unambiguous identification of one factor with eigenvalue 2.9 on exploratory factor analysis), strong ability to discriminate between physician-estimated disease activity states (p< 0.001), and fair responsiveness to clinically important change over time (standardized response mean 0.8 among patients judged as improved by the parents). The ParJDMAI correlated strongly with physician-centred measures of disease activity. CONCLUSION: The ParJDMAI was found to be feasible and to possess good measurement properties. It also proved to potentially serve as surrogate for physicians' evaluations. Completion of the ParJDMAI through digital technologies may provide a reliable and pragmatic approach to build a remote patient monitoring program.