Clinical Heterogeneity of Interstitial Lung Disease in Polymyositis and Dermatomyositis Patients With or Without Specific Autoantibodies.

BACKGROUND

The aim of this study was to compare the heterogeneity of interstitial lung disease (ILD) in patients with polymyositis and dermatomyositis (PM/DM) according to serological type.

METHODS

A total of 182 patients with PM/DM-ILD were observed retrospectively. Antiaminoacyl-tRNA synthetase (ARS) and antimelanoma differentiation-associated gene5 (MDA5) antibodies were screened using immunoblotting approach. The patients with ILD were divided into 3 groups: MDA5 (with anti-MDA5 antibody), ARS (with anti-ARS antibody) and MSN (without anti-MDA5 or anti-ARS antibody) group. Pulmonary features, treatment responses and prognoses were compared among the groups.

RESULTS

A higher percentage of rapidly progressive ILD (RP-ILD) occurrences (55.8% versus 25% versus 16.9%, P < 0.001) was observed in the MDA5 group compared to ARS and MSN groups. The MSN group experienced lower dyspnea (48.2% versus 79% versus 71.4%, P = 0.001) and fever (18.1% versus 39.5% versus 37.5%, P = 0.01) frequencies compared to MDA5 and ARS groups. Response to 6-month treatment among 95 patients showed highest deterioration ratio (70%, P = 0.001) of ILD in the MDA5 group. Additionally, the highest frequency of ILD improvement (60%, P = 0.04) was observed in the ARS group. During the observation period, 24 patients died of respiratory failure. The 5-year survival rates were significantly lower in MDA5 group (50.2%) compared to ARS group (97.7%) or the MSN group (91.4%) (P < 0.001).

CONCLUSIONS

MDA5-ILD was associated with severe pulmonary manifestations, poor response to treatment and aggravated prognosis. The ARS-ILD group had favorable treatment response and prognosis. MSN-ILD patients had relatively worse treatment response and prognosis compared to the ARS group, even though they expressed milder pulmonary manifestation.