Validation of Calcinosis Durometer Measurements in Juvenile and Adult Dermatomyositis

Authors

• M Nelson
• L Rider
• H Kim
• S Gillespie
• V Do
• J Fuller
• K Rouster-Stevens
• A Schifffenbauer

Abstract

Objective: Dermatomyositis (DM) and juvenile dermatomyositis (JDM) are idiopathic inflammatory myopathies affecting multiple organs, including skeletal muscle and skin. Calcinosis, a known complication of DM/JDM, is associated with significant morbidity. Tools to assess calcinosis in DM/JDM patients have been inadequately validated. The goal of this study was to determine the reliability of durometer measurements of calcinosis in JDM and DM patients.

Methods: Calcinosis firmness was measured using handheld digital durometer with a continuous scale across 3 institutions. Five investigators examined DM/JDM calcinosis lesions by durometry, optimally recording three readings per site, as well as control readings unaffected by calcinosis in similar anatomic areas. Intra-rater and inter-rater intraclass correlations were evaluated.

Results: We enrolled 57 patients and gathered 709 durometric measurements of both calcinosis and control lesions (443 calcinosis; 266 control) over eleven anatomic regions by durometry. Intra-rater intraclass correlation was high with repeat measurements, including at control and calcinosis sites, indicating good intra-rater reliability. Inter-rater reliability was moderate to good over repeat measurements in the upper neck/clavicle, forearms, upper arms, back/torso, posterior calf, and elbows, with the exception of the thigh and anterior calf, which were below the threshold of acceptability. Durometry readings of calcinosis lesions were statistically higher than control lesions in the following locations: upper neck/clavicle, upper arms/forearms, elbows, hand/wrists, buttocks, thigh, calf and foot. Calcinosis lesions overall were harder compared to control lesions.

Conclusion: Our study identifies durometry as a reliable tool in assessing targeted lesions of calcinosis lesions in DM/JDM patients.

Scientific Focus Area: Clinical Research

This page was last updated on Monday, September 25, 2023