Background/Purpose:   Anti-MDA5 Ab positive dermatomyositis (DM) is a unique subset of inflammatory myopathy characterized by non- or mild muscle weakness, skin manifestation such as palmar pustles, and high prevalence of rapidly progressive interstitial lung disease (RP-ILD) with resistance to therapies. RP-ILD determines prognosis of DM patients with anti-MDA5 Ab, and intensive immunosuppressive therapy, a combination therapy with high dose glucocorticoid (GC), cyclophosphamide (CY) and calcineurin inhibitors such as cyclosporine (CsA) is required for ILD. However, there are patients who fail to response the treatment and it is not clear what patients are resistant to intensive immunosuppressive therapy. The aim of the present study is to identify poor prognostic factors in RP-ILD in DM positive for anti-MDA5 Ab.

Methods: Retrospective analysis was performed on consecutive 15 anti-MDA5 + patients with RP-ILD among 63 inflammatory myositis who admitted our department from 2007 to 2015. RP-ILD was defined by ILD with worsening of respiratory condition and chest infiltration within 1 month. Anti-MDA Ab was measured by ELISA in our lab. All patients were treated with combination of high dose GC (pulse therapy followed by 60mg/day of predonisolone), IVCY (500-750mg every 2-4 week) and CsA (12h intravenous administration adjusted to Cmax above 1000ng/ml during infusion and Cmin 200-250 ng/ml. Imaging analysis was conducted by 3 independent investigators.

Results:   Subjects were 15 patients of 8 males and 7 female with age of 57.9±10.4 year; 14 of them were amyopathic DM (DM). Eight of them died within 6 month (7 died of respiratory failure), and 7 survived by immunosuppressive therapy. Comparison of clinical features of poor and good prognosis was shown in Table 1. Serum ferritin levels before immunosuppressive therapy and increase in ferritin levels during the treatment was high in patients with poor prognosis. The numbers of lung fields with ground glass opacities (GGO) was large in the dead. New infiltrate during the therapy was frequently found in the dead. Based on these findings, we made a score to predict the prognosis; add points of 3 factors:1) if serum ferritin levels before treatment >1000ng/ml or increase in ferritin levels during therapy >2000 ng/ml: point 1, if no: 0; 2) if numbers of lung fields (rt/lt upper, middle and lower, total 6 fields) with GGO > 4: point 1, or if <3: point 0; and if lung infiltrate was improved within 2 week starting therapy: point -1, no change: 0, and worsened or new infiltrate: 1. When the score was 3 and2, 3/3 (100%) and 5/7(71%) died, respectively while all of score <2 survived.

Conclusion: When serum ferritin levels are elevated before treatment , ferritin levels are ibncrased during therapy, many lung fields are affected by GGO and new lung infiltrate emerged during the therapy, the prognosis of ILD of DM patients with anti-MDA5 Ab is poor in spite of intensive immunosuppressive therapy.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/serum-ferritin-levels-distribution-of-ground-glass-opacities-and-new-development-of-lung-infiltration-during-therapy-predict-prognosis-of-interstitial-lung-disease-in-anti-mda5-ab-positive-dermatomyo/