Clinical features and prognosis of anti-MDA5-positive dermatomyositis with coexistent anti-aminoacyl-tRNA synthetase antibodies

ObjectivesThis study aimed to evaluate the incidence and clinical significance of coexistence of anti-aminoacyl-tRNA synthetase (anti-ARS) antibody in patients with anti-melanoma differentiation-associated gene 5-positive dermatomyositis (anti-MDA5 + DM). MethodsWe assessed a cohort of 246 consecutive patients with anti-MDA5 + DM. Clinical characteristics and survival rates were compared between patients with and without anti-ARS antibodies. ResultsOf these 246 patients, 15 (15/246, 6.1%) were positive for anti-ARS antibodies. The anti-ARS-positive group had a higher proportion of mechanic's hands (53.3% vs 25.5%, P = 0.019), and the positivity rates for antinuclear antibody (ANA) (80.0% vs 50.6%, P = 0.033) and anti-Ro52 antibodies (93.3% vs 62.3%, P = 0.013) were also higher. However, the CRP levels were comparatively low [4.0 (0.5, 7.8) vs 6.0 (3.1, 12.2), P = 0.019]. In the overall population, no difference in survival rates was observed between anti-MDA5 + DM patients with or without anti-ARS antibodies (log-rank P = 0.339). The multivariate Cox regression analysis revealed that elevated lactate dehydrogenase (LDH) levels and the presence of rapidly progressive interstitial lung disease (RPILD) were associated with poor prognosis [hazard ratios of 1.002 (95% CI 1.001, 1.002, P < 0.001) and 11.096 (95% CI 5.006, 24.598, P < 0.001), respectively]. ConclusionAmong the 246 patients with anti-MDA5 + DM, only 15 patients (6.1%) tested positive for anti-ARS antibodies. The presence of anti-ARS antibodies is associated with the occurrence of mechanic's hands, as well as an increased positive rate of ANA and anti-Ro52 antibodies. Elevated LDH levels and the presence of RPILD are poor prognostic risk factors for patients with anti-MDA5 + DM. Key Points center dot The presence of anti-ARS antibodies is associated with the occurrence of mechanic's hands, as well as an increased positive rate of ANA and anti-Ro52 antibodies.center dot Elevated LDH levels and the presence of RPILD are poor prognostic risk factors for patients with anti-MDA5 + DM.center dot Understanding the clinical characteristics of these patients will help clinicians to develop individualised treatment plans for each patient.