# Reliability of durometry to assess firmness of calcinosis lesions in Juvenile and adult dermatomyositis

## TL;DR

This study evaluates the reliability of using a durometer to measure the firmness of calcinosis lesions in dermatomyositis patients.

## Contribution

The study introduces durometry as a novel and reliable quantitative tool for assessing calcinosis in dermatomyositis.

## Key findings

- Durometry showed high intra-rater reliability and moderate to good inter-rater reliability in most anatomical regions.
- Calcinosis lesions were firmer than control sites, and measurements correlated with physician assessments.
- Inter-rater reliability was poor in specific regions like the thigh and anterior calf.

## Abstract

Dermatomyositis (DM) and juvenile dermatomyositis (JDM) are inflammatory myopathies affecting multiple organs, including muscle and skin. Calcinosis is a complication of DM/JDM that causes significant morbidity; however, few tools exist to assess calcinosis in DM/JDM patients This study aimed to evaluate the reliability of durometry measurements to assess the firmness of calcinosis lesions in DM and JDM patients.

Calcinosis firmness was measured using a handheld digital durometer. Six investigators across 3 institutions examined DM/JDM calcinosis lesions by durometry, as well as control readings in healthy unaffected skin/subcutaneous tissue in similar anatomic areas, recording three readings per site. Intra-rater and inter-rater intraclass correlations were evaluated.

We enrolled 57 patients and gathered 709 measurements (443 calcinosis lesions; 266 control lesions) over eleven anatomic regions. Intra-rater reliability was high across sites, while inter-rater reliability varied, being moderate to good in most areas, but poor in the thigh and anterior calf. Durometry readings were higher in calcinosis lesions than control sites overall. Measurements moderately correlated with qualitative physician assessments. Due to our study’s cross-sectional nature, we could not assess calcinosis over time.

Durometry is a novel, reliable, quantitative measure in assessing and characterizing targeted calcinosis lesions of DM/JDM patients.