Although a number of clinical predictive models were developed to predict postoperative pulmonary infection, few predictive models have been used in elderly patients. In this study, the researchers aim to compare different algorithms to predict postoperative pulmonary infection in elderly patients and to assess the risk of postoperative pulmonary infection in elderly patients.

Inclusion Criteria:

1. age ≥ 65 years
2. patients who were mechanically ventilated under major surgery

Exclusion Criteria:

1. preoperative tracheal intubation
2. preoperative pneumonia
3. organ transplantation
4. missing data

Elderly patients underwent surgery at the tertiary hospital Hospital from January 2014 to December 2019.