The AUC of previously reported risk factors; age ≥ 75 years, BMI < 21.0 kg/m², Brinkman index ≥ 800, and short MPTs were added to predict postoperative late-onset pneumonia. The blue curve represents previously reported risk factors, which has an AUC of 0.678 (95% confidence interval: 0.588–0.769). The red curve represents the addition of short MPT, which has an AUC of 0.726 (95% confidence interval: 0.645–0.807). Adding MPT to previously reported risk factors significantly increased the AUC (P = 0.045).