Comparisons with the respective groups without respiratory failure by the Student’s t test: ∗p-non-significant; ∗∗p < 0.05; #p < 0.001; ##p < 0.0001. Abbreviations are as follows: ALT, alanine aminotransferase; aPTT, activated partial thromboplastin time; AST, aspartate aminotransferase; APACHE, acute physiology and chronic health evaluation; CCI, Charlson’s comorbidity index; INR, international normalized ratio; PSI, pneumonia severity index; SD, standard deviation; SOFA, sequential organ failure assessment