SFTPD and idiopathic interstitial pneumonia: In the Cox analysis adjusted for treatment with an immunosuppressive agent, baseline cardiovascular diseases, higher GAP stage (≥II), and higher serum SP-D level (≥194.7 ng/mL) were significant prognostic factors for IPF (HR [95 % CI], 2.37 [1.03–5.44], 3.63 [1.47–8.93], and 3.21 [1.21–8.48]) (Table 4).