APOA1 and pneumonia: Currently, NLR, HCT, CRP, PCT, DD, PSI score, and APACHE II score are commonly used in China to predict the prognosis of patients with severe pneumonia [21], [22], and this study analyzed the above indicators and found that LDH and ApoA1 levels in the death group of patients with severe pneumonia were higher than those in the survival group, while the distribution levels of the remaining indicators did not differ significantly between the death and survival groups.