A total of 11 variables were included in the multivariate analysis model, such as age >69 years, FiO2 >39%, history of stroke, pH < 7.35, platelet <150,000/μL, history of coronary artery disease, hemoglobin, BUN, C-reactive protein, PaO2/FiO2 and PaCO2 on admission day 7. Here, CRP is linked to coronary artery disorder.