Introduction:
This study aimed to investigate the association between ANA and clinical characteristics as well as prognosis in a cohort of patients with anti-MDA5+ DM.

Material and methods:
We conducted a systematic retrospective study of medical records from Nanjing Medical University myositis associated interstitial lung disease (ILD) contort.

Results:
A total of 246 patients with anti-MDA5+ DM were enrolled in this study, with 28.5% males and 71.5% females. The median age was 53.0 years, the median disease duration was 2 months, and the median follow-up period was 12.0 months. ANA positivity rate at baseline was 52.4% in anti-MDA5+ DM patients. The ANA-positive group showed significantly higher positivity rates of anti-Ro52 antibodies (72.9% vs 54.7%, p=0.003) and anti-aminoacyl-tRNA synthetase (anti-ARS) antibodies (9.3% vs 2.6%, p=0.033) compared to the ANA-negative group, but lower ALT levels [39.0 (21.5, 79.3) vs 51.3 (36.5, 95.8), p=0.006].In a subgroup analysis of the ANA-positive group, MDA5+++ patients had a higher incidence of RPILD compared to the MDA5+ group (P=0.028). In the ANA negative subgroup analysis, MDA5+++ patients had a higher mortality rate and worse prognosis compared to the MDA5+ group (P=0.026). Multivariate COX regression analysis showed that elevated LDH levels and the presence of rapidly progressive interstitial lung disease (RPILD) were associated with poor prognosis in ANA-negative anti-MDA5+ DM patients [hazard ratios of 1.002 (95% CI 1.001, 1.003, P = 0.020) and 13.694 (95% CI 15.032, 37.267, P < 0.001), respectively].

Conclusions:
ANA is frequently found in patients with anti-MDA5+ DM. High titres of anti-MDA5 antibodies are associated with mortality and RPILD.