Clinical Features and a Nomogram for Predicting Clinical Response in Juvenile Dermatomyositis-Associated Interstitial Lung Disease

Juvenile dermatomyositis (JDM) is a rare autoimmune disease; when accompanied by interstitial lung disease (ILD), it is a major cause of morbidity and mortality. However, data on clinical features and prognosis of JDM-ILD in Chinese pediatric populations remain limited. The aim of this study was to characterize the clinical features, treatment options, and prognosis of JDM-ILD in Chinese pediatric patients, and to develop a nomogram for predicting clinical response.

We retrospectively enrolled patients with JDM-ILD from Beijing Children's Hospital (May 2015-January 2026). Demographic, clinical, laboratory, treatment, and prognostic data were collected. Clinical response was assessed through a combination of Pediatric Rheumatology International Trials Organisation (PRINTO)-defined clinically inactive disease (CID), respiratory symptoms, and high-resolution computed tomography (HRCT). Independent prognostic factors were identified using Cox regression analysis and incorporated into a nomogram. Model performance was assessed using concordance index (C-index), calibration curves, and decision curve analysis (DCA).

Among the 244 patients included (55.7% female, median onset age 5.7 years), antimelanoma differentiation-associated gene 5 (MDA5; 32%) and antinuclear matrix protein 2 (NXP2; 13.9%) were the most prevalent autoantibodies. At the last follow-up visit, 202 patients (82.8%) achieved CID, with CID rates increasing progressively over time. Three patients who tested positive for anti-MDA5 antibody died of rapidly progressive ILD (RP-ILD; median survival 2.7 months). Multivariable Cox regression identified combination therapy with Janus kinase inhibitors (JAKi; hazard ratio [HR] 2.09, 95% CI 1.25-3.50) or interleukin 6 inhibitors (IL-6i; HR 1.83, 95% CI 1.07-3.12) and Gottron sign (HR 1.80, 95% CI 1.10-2.96) as favorable factors for CID, whereas high-risk status (HR 0.23, 95% CI 0.10-0.57), higher Disease Activity Score (DAS) skin score (HR 0.71, 95% CI 0.48-1.00), and higher neutrophil-to-lymphocyte ratio (NLR; HR 0.84, 95% CI 0.72-0.97) predicted lower probability of CID. The nomogram showed predictive performance in both the training cohort (area under the curve [AUC] 0.67, 0.77, and 0.78 at 1, 3, and 5 years, respectively) and the testing cohort (AUC 0.60, 0.78, and 0.77 at 1, 3, and 5 years, respectively).

This nomogram for predicting clinical response in Chinese pediatric patients with JDM-ILD integrates clinical features and treatment variables to enable individualized risk stratification. Combination therapy with JAKi or IL-6i demonstrates promising efficacy and may improve outcomes.