[A study of differences in the course of anti-MDA5-positive dermatomyositis and early diagnosis of rapidly progressive interstitial lung disease].

Objective: To investigate the clinical characteristics and early diagnosis of rapidly progressive interstitial lung disease (RP-ILD) in patients with anti-MDA5-positive dermatomyositis of different disease stages. Methods: The clinical data of 249 patients with anti-MDA5 antibody positive DM collected from Inflammatory myopathy and Connective tissue Disease-Associated Interstitial Lung Disease Alliance of Nanjing Medical University were analyzed retrospectively, of which 207 cases were in the short-duration group (≤6 months), and 42 cases were in the long-duration group (>6 months).The measurement data conforming to the normal distribution should be subjected to t test, the measurement data of non-normal distribution should be subjected to Mann-Whitney U test, and the counting data shoulb be subjected to χ2 test. The risk factors were analyzed by binary logistic regression, and the predictive value of each risk factor was evaluated by drawing ROC curve. The survival analysis was performed by Kaplan-Meier method. Results: The incidence of muscle weakness, rash, Gottron's sign, V sign, perlungual erythematosus and mechanic's hands was higher in patients in the short course group than in the long course group, whereas the incidence of heliotrope rash, shawl sign, and arthritis was lower (P>0.05). Furthermore the incidence of ILD and RP-ILD in the patients in the short-course group was significantly higher, and the difference was statistically significant (P<0.05).The mortality rate in the short-course group (29.9%) was significantly higher than that in the long-course group (4.8%), and the difference was statistically significant (P<0.05). The levels of ALT, AST, LDH, CK and CRP and the anti-Ro52 positivity were higher in the short-course group than in the long-course group, and the difference was statistically significant (P<0.05).The differences in ESR, ferritin levels and ARS positivity between the two groups were not statistically significant (P>0.05). In the short-course group, male and anti-Ro52 were independent risk factors for RP-ILD in anti-MDA5-positive dermatomyositis patients, while rash and arthritis were protective factors for RP-ILD. The results of the ROC curve showed that the anti-Ro52 had a better diagnostic value for RP-ILD in anti-MDA5-positive dermatomyositis patients in the short-course group, with a sensitivity of 54.62% and a specificity of 89.77% (P<0.001). specificity 89.77%, and an AUC of 0.722 (P<0.001). A total of 60 patients died, including 58 patients in the short-course group and 2 patients in the long-course group, and the survival time of patients in the short-course group was shorter than that in the long-course group, with a statistically significant difference (P<0.001). Conclusion: Patients with short-duration anti-MDA5 antibody positive DM have an increased risk of RP-ILD, a higher mortality rate, and a shorter survival time than patients with long-duration disease, Anti-Ro52 may be a poor prognostic factor.