Nomogram to predict dermatomyositis prognosis: a population-based study of 457 cases.

OBJECTIVES: Dermatomyositis (DM) is a systemic autoimmune disease, which typically affects the striated muscle with a variable involvement of the skin and other organs. Clinically amyopathic DM (CADM) is a combination of hypomyopathic DM (HDM) and amyopathic DM (ADM), with a characteristic of skin-predominant lesions. To date, large-scale studies on the prognostic factors of DM/CADM have been limited. The aim of this study is to evaluate the prognostic values of clinical manifestations in DM/CADM and to develop a prognostic nomogram for DM/CADM. METHODS: A development cohort (n=239), an internal validation cohort (n=128) and an external validation cohort (n=90) were included in this study. Overall survival (OS) was estimated by the Kaplan-Meier method. Univariate and multivariate Cox proportional hazards regression analyses were performed. Cox proportional hazards model and forward stepwise selection with the Akaike information criterion were used for multivariate analysis of prognostic factors. The concordance index (C-index) and calibration curve were calculated to evaluate the predictive accuracy of the proposed nomogram. RESULTS: Rapidly progressive interstitial lung disease (RP-ILD) and erythrocyte sedimentation rate (ESR) were identified as risk independent prognostic factors, with antinuclear antibodies (ANA) was identified as protective independent prognostic factors, for DM/CADM. A prognostic nomogram was formulated based on these three predictors. The C-index of the proposed nomogram in the development cohort was 0.874 (95%CI, 0.819-0.929). The predictive accuracy of the proposed nomogram was further validated in the internal validation cohort, with a C-index of 0.799 (95%CI, 0.681-0.917). Furthermore, the C-index was 0.864 (95%CI, 0.699-1.000) in the external validation cohort, indicating a good calibration ability. This proposed nomogram showed a promising predictive accuracy on the prognosis of DM/CADM. CONCLUSIONS: RP-ILD, ANA and ESR are prognostic factors for DM/CADM. The proposed nomogram based on these three factors could accurately predict the 10-year OS probabilities of patients with DM/CADM.

A Clinical Risk Model to Predict Rapidly Progressive Interstitial Lung Disease Incidence in Dermatomyositis.

Background: Rapidly progressive interstitial lung disease (RP-ILD) is a fatal complication of dermatomyositis (DM) and clinically amyopathic DM (CADM). The objective of this study was to evaluate risk markers associated with RP-ILD incidence in patients with DM/CADM and to develop a RP-ILD risk prediction (RRP) model. Methods: The clinical records of 229 patients with DM/CADM from Peking University People's Hospital, and 97 patients from four other independent clinical centers were retrospectively reviewed. Univariate and multivariate logistic regression analyses were performed to identify independent risk factors associated with later RP-ILD incidence to build a risk score model. The concordance index (C-index) and calibration curve were calculated to evaluate the predictive accuracy of the RRP model. Results: A multiparametric RRP model was established based on weighted clinical features, including fever (yes, 5; no, 0), periungual erythema (yes, 6; no, 0), elevated CRP (yes, 5; no, 0), anti-MDA5 antibody (positive, 8; negative, 0), and anti-Ro-52 antibody (positive, 6; negative, 0). Patients were divided into three risk groups according to the RRP total score: low, 0-9; medium, 10-19; high, 20-30. The C-index and calibration curve of the RRP model showed a promising predictive accuracy on the incidence of RP-ILD. Conclusion: The RRP model might promisingly predict the incidence of RP-ILD in DM/CADM patients to guide early individual treatment and further improve the prognosis of DM/CADM patients.