APOA1 and susceptibility to pneumonia measurement: The AUC of LDH combined with ApoA1 for predicting death in patients with severe pneumonia was 0.873 (95% CI (0.779~0.967)), with a higher area under the line than the test alone, sensitivity of 85.14% and specificity of 82.83%, making it a prognostic indicator with a higher combined sensitivity and specificity compared to other indicators.