SHBC1003

J.Z.LOW¹, C G CHUA¹, K L W¹, W Y L¹, M M¹ 

Tan Tock Seng Hospital¹

Anti-melanoma differentiation-associated gene 5 (MDA5) Ab positive associated dermatomyositis (DM) patients with rapidly progressive-interstitial lung disease (RP-ILD) have poor survival rates.

A chart review (January 2015 to July 2019) was undertaken for 84 DM patients at TTSH with positive myositis specific antibodies.

18 out of 84 were anti-MDA5-Ab positive. Features more common in the anti-MDA5 Ab positive vs. the anti-MDA5 Ab negative cohort included: inverse Gottron’s papules (27.8% vs. 3%, p=0.001) palmar papules (27.8% vs. 0%, p<0.001), violaceous rash (55.6% vs. 16.7%, p=0.001), cutaneous ulcers (66.7% vs. 6.1%, p=<0.001), clinically amyopathic DM (50% vs. 22.7%, p=0.023) and polyarthritis (38.9% vs. 12.1%, p=0.0009). The anti-MDA5 Ab positive cohort had a lower median creatine kinase versus the anti-MDA5 Ab negative cohort; 328 [60-3254] vs. 1318 [61-36776], (p=0.0027).

ILD was more common in the anti MDA5 Ab positive vs. anti-MDA5 Ab negative cohort (61.1% vs. 34.8%; p=0.044). Of these anti-MDA5 Ab positive with ILD, 45.5% had RP-ILD, 27.3% had either chronic ILD or asymptomatic ILD respectively. In contrast, only 17.4% had RP-ILD in the anti-MDA5 Ab negative cohort. The mortality rate in the anti-MDA5 Ab positive vs. negative cohort was higher (33.3% vs. 24.2%).

Patients with both Ro-52 and MDA5 Ab positivity had a higher incidence of cutaneous ulcers, pneumothorax, ILD and mortality.  Of those anti-MDA5-Ab positive cases that survived, treatment included either rituximab and/or tofacitinib.

Anti-MDA5 Abs-associated DM is associated with increased mortality. Better recognition of their distinct clinical features will enable early diagnosis, risk stratification and aggressive treatment to improve survival.