BTG3 and Skin ulcer: Smooth curve fitting, test for trend, and COX regression analysis by R Studio were utilized to evaluate the mortality risk with the Crude model and Adjusted model, adjusted variables in the adjusted model including age, gender, smoke, duration, mechanic hand, heliotrope rash, Gottron’s sign, V sign, shawl sign, periungual erythema, Raynaud phenomenon, skin ulcers, muscle weakness, arthritis, fever, ANA, RF, RO52, ALB, ALT, AST, CK, LDH, ESR, RP-ILD, CRP.