Fig. 2

Survival curves and infection-free rates in patients with polymyositis/dermatomyositis-interstitial lung disease (PM/DM-ILD) 6 months after baseline. Patients are divided into two groups based on the cutoff points of individual variables, which were determined by receiver operating characteristic analysis. a high score in zone A and low arterial partial pressure of carbon dioxide (PaCO₂) are significantly associated with early death. The cutoff point for zone A is 1.3 (between 1 and 2) and that for PaCO₂ is 34.5 mmHg. b High serum KL-6, high initial prednisolone (PSL) dose and treatment with combination therapy are significantly associated with serious infections. The cutoff point for KL-6 is 670 U/ml and that for initial PSL dose is 0.55 mg/kg body weight per day