CRP and respiratory failure: Then we included age, gender, white blood cell, NLR, IL-6, CRP, LDH, D-dimer, PT level for a multivariate regression analysis, as a result, NLR (OR=2.112, 95%CI:1.053, 4.234, p=0.035), LDH (OR=1.031, 95%CI: 1.003, 1.061, p=0.030), PT (OR=2.008, 95%CI: 1.048, 3.848, p=0.036) were found to be independent risk factors for the COVID-19 elderly patients combined with respiratory failure.