PRTN3 and rheumatoid arthritis: ROC curves for anti-MDA5 Abs (A), RF (B), ACPA (C) and multiple logistic regression analysis with anti-MDA5 Abs, age (years), Steinbrocker stage (1–4), and smoking status (current smoker: 2, past smoker: 1, never smoker: 0) (D) were generated to compare CLD(+) and CLD(−) RA.