AbstractIntroductionThe prognosis of anti‐MDA5 antibody‐positive dermatomyositis/clinically amyopathic dermatomyositis‐associated interstitial lung disease (MDA5‐DM/CADM‐ILD) is poor. This study was to evaluate the effect of serum soluble CD206 (sCD206), a biomarker of macrophage activation, on predicting the interstitial lung disease (ILD) deterioration and prognosis for MDA5‐DM/CADM‐ILD.MethodsForty‐one patients diagnosed with MDA5‐DM/CADM‐ILD were retrospectively included. The clinical data were analyzed. Serum sCD206 levels were measured in 41 patients and 30 healthy controls. The relation between sCD206 levels and ILD deterioration was assessed. Receiver operating characteristic (ROC) curve was generated to determine the optimal cut‐off value of sCD206 for predicting outcome. The association between sCD206 and survival was examined.ResultsThe median serum sCD206 level in patients was significantly higher than healthy controls (464.1 ng/mL vs. 349.1 ng/mL,P= 0.002). In DM/CADM patients, the sCD206 level was significantly higher in patients with acute/subacute interstitial lung disease (AILD/SILD) than those with chronic interstitial lung disease (CILD) (539.2 ng/mL vs. 309.4 ng/mL,P= 0.005). The AUC of sCD206 was 0.885 for predicting mortality (95% CI 0.779–0.990). Patients were divided into two groups: sCD206 high level group (≥400 ng/mL) and sCD206 low level group (<400 ng/mL). Patients with sCD206 high level had significantly decreased survival rate than those with low level (25% vs. 88%,P< 0.001). The adjusted hazard ratio of sCD206 for mortality was 1.003 (adjusted for age and gender,P< 0.001), with sCD206 high level associated with higher death risk (HR 4.857,P= 0.006).ConclusionSerum sCD206 might be a potential predictor of ILD deterioration and prognosis for Chinese patients with MDA5‐DM/CADM‐ILD.