Objective To evaluate the clinical relationship between serum carcinoembryonic antigen (CEA) and mortality of anti-melanoma differentiation associated gene 5 (MDA5) antibody positive dermatomyositis with interstitial lung disease (ILD). MethodsThe consecutive clinical data of 214 patients with anti MDA5 antibody positive dermatomyositis from West China Hospital of Sichuan University from February 2017 to September 2019 were collected retrospectively, including demographic, laboratory examination and imaging examination data. Patients were divided into CEA elevated group (CEA≥4.63 ng/mL) and CEA normal group (CEA<4.63 ng/mL) according to CEA level. R4.1.2 software was used for statistical analysis of all data, and Kaplan Meier method was used to draw the survival curve. Cox proportional hazard model was used to analyze the survival of patients with ILD, and to explore the risk factors associated with the survival of patients with anti-MDA5 antibody positive dermatomyositis with ILD. Results There were 180 patients with ILD who met the inclusion and exclusion criteria, 57 patients with rapidly progressive pulmonary interstitial fibrosis (RPILD), and 123 patients without RPILD; 121 women and 59 men, with an average age of 50.2±10.7 years; The average follow-up was 23.5 months, and 52 patients died. Univariable analysis suggested that CEA≥4.63 ng/mL, smoking, RPILD, lactate dehydrogenase (LDH) ≥321 IU/L, albumin<30 g/L and dyspnea were risk factors associated with death in patients with anti MDA5 dermatomyositis combined with ILD. Multivariable Cox regression analysis showed that CEA≥4.63 ng/mL [hazard ratio (HR) =3.01, 95% confidence interval (CI) 1.23 - 7.32, P=0.015], RPILD (HR=3.87, 95%CI 2.09 - 7.19, P<0.001), smoking (HR=2.37, 95%CI 1.25 - 4.47, P=0.008), LDH≥321 IU/L (HR=2.47, 95%CI 1.23 - 4.96, P=0.011), albumin<30 g/L (HR=2.57, 95%CI 1.38 - 4.78, P=0.003) were independent predictors for mortality. ConclusionsSerum CEA level can be used as a clinical prognostic predictor in patients with anti-MDA5 positive dermatomyositis and ILD. RPILD, smoking, LDH≥321 IU/L, and albumin<30 g/L are independent predictors for mortality.