A clinical analysis of prognostic factors for dermatomyositis-associated interstitial lung disease

Objective: Interstitial lung disease (ILD) is a common and life-threatening manifestation of dermatomyositis (DM). However, little is known about the factors that influence the prognosis of DM-ILD. The present study aimed to evaluate the characteristics and outcomes of ILD in DM and to determine the prognostic factors of DM-ILD. Methods: A retrospective analysis of DM-ILD was performed by survival analysis. Clinical manifestations and laboratory data were analyzed. The ILD-associated survival rates were estimated by using the Kaplan-Meier method to identify potential prognostic factors. Factors with P values <= 0.10 were subjected to a multivariate Cox regression analysis. P values <= 0.05 were considered statistically significant. Results: Overall, 103 DM patients with ILD were enrolled in the study. The mean follow-up period was 21.9 months (range, 2-120 months). The clinical presentation of ILD was the acute/subacute form in 48 patients (46.6%) and the chronic form in 55 patients (48.2%). ILD-associated mortality was 34.9%. The statistical analysis suggested that age over 60 years, the acute/subacute form of ILD, heliotrope sign, ESR>20 mm/h, CRP>10 mg/L and hypocalcemia are independent predictors of poor outcomes in DM-ILD. Moreover, negative correlations between serum calcium and the levels of CRP and ESR were found in DM-ILD. Conclusions: Age over 60 years, the acute/subacute form of ILD, heliotrope sign, ESR>20 mm/h, CRP>10 mg/L and hypocalcemia predict poor outcomes in DM-ILD patients. The serum calcium level may be an inflammatory biomarker in DM-ILD patients.