Background/Purpose: Interstitial lung disease (ILD) associated with antibodies to melanoma differentiation-associated protein 5 (MDA5 ab) in patients with dermatomyositis (DM) has been associated with a rapid decline in lung function and high mortality early in disease. The current work evaluated long-term changes in lung function in a longitudinal MDA5 ab positive DM cohort in North America.

Methods: We identified DM patients with MDA5 ab in a single center longitudinal cohort of 355 adult patients with idiopathic inflammatory myopathies (IIM). Patient clinical characteristics and longitudinal pulmonary function tests (PFT), echocardiograms, and high-resolution computed tomography (HRCT) chest scan results were collected by chart review.

Results: 30 DM patients (8.5%) of the IIM cohort had confirmed positive MDA5 ab testing. The clinical characteristics of patients with ILD (n=24, 80%) and without ILD (n= 6, 20%) by HRCT are shown in Table 1. Patients without ILD were younger and more likely to present with inflammatory arthritis. Patients with ILD had an aggressive disease phenotype with 75% (22/24) requiring initial hospitalization. Two ILD patients died of rapidly progressive ILD within 3 months of cohort entry. ILD patients were treated predominantly with combination immunotherapy (Table 1) during longitudinal follow-up and remained on combination immunotherapy with 3.1 ± 1.3 (mean ± SD) individual therapies at the last follow-up visit available for this analysis. Non-ILD patients remained on a mean combination of 2.0 ± 1.3 therapies at the last follow-up visit (p =0.06 vs ILD group). 18 ILD patients had short-term (~2 yr) follow-up PFT data available (1.8 ± 0.6 years from baseline PFT), and 10 ILD patients had both short-term (~2 yr) and long-term follow-up PFT data available (2.0 ± 0.6 and 6.8 ± 3.4 years from baseline PFT, respectively).In analysis of both cohorts, significant improvements in % predicted DLCOHg, FVC, and FEV1 were noted over time (Tables 2-3). In the long-term cohort, continued improvement in pulmonary function beyond the initial follow-up visit at ~2 years with progressive increases in % predicted DLCOHg, FEV1, and FVC at ~ 7 years were noted (Table 3).

Conclusion: A low mortality rate and significant improvements in pulmonary function over long-term follow-up were observed in a North American cohort of MDA5 ab positive patients with ILD treated predominantly with combination immunomodulatory therapy. These results emphasize the importance of early identification and aggressive treatment of MDA5 ab positive DM patients with ILD who may have reversible impairment in lung function.

« Back to ACR Convergence 2023

ACR Meeting Abstracts - https://acrabstracts.org/abstract/long-term-changes-in-lung-function-in-melanoma-differentiation-associated-protein-5-mda5-antibody-positive-dermatomyositis-patients-experience-of-a-single-center-longitudinal-cohort-in-north-americ/