Postoperative pneumonia after craniotomy: incidence, risk factors and prediction with a nomogram

Background Postoperative pneumonia is the third most common complication in surgical patients. However, little is known regarding pneumonia after craniotomy, which is the most common surgical procedure in neurosurgery. Aim To investigate the incidence of pneumonia and its association with the length of hospital stay, identify risk factors, and build a nomogram as a prediction model. Methods The study population was based on the American College of Surgeons' National Surgical Quality Improvement Program database from 2005 to 2017. Both multi-variate logistic regression models and linear regression models were employed. Findings The overall incidence rate of postoperative pneumonia was 3.11% in a total of 57,201 surgical procedures. Risk factors were age >55 years, male gender, low body mass index (BMI), diabetes, functional dependence, ventilator dependence, history of severe chronic obstructive pulmonary disease, hypertension, systemic sepsis, white blood cell count >12,000, emergency case, American Society of Anesthesiologists class ≥3, general anaesthesia and total surgical time >240 min. Ten featured factors were used in the nomogram (C-statistic=0.803). Postoperative pneumonia was associated with extended hospital stay. Compared with other postoperative complications, pneumonia had the second-highest impact on the extension of hospital stay (by 4.7 days). Conclusion This study identified several pre-operative risk factors for postoperative pneumonia after craniotomy. Novel factors including male gender and low BMI warrant further investigation. This novel nomogram could serve as a reliable tool to evaluate the risk of postoperative pneumonia pre-operatively. Postoperative pneumonia is the third most common complication in surgical patients. However, little is known regarding pneumonia after craniotomy, which is the most common surgical procedure in neurosurgery. To investigate the incidence of pneumonia and its association with the length of hospital stay, identify risk factors, and build a nomogram as a prediction model. The study population was based on the American College of Surgeons' National Surgical Quality Improvement Program database from 2005 to 2017. Both multi-variate logistic regression models and linear regression models were employed. The overall incidence rate of postoperative pneumonia was 3.11% in a total of 57,201 surgical procedures. Risk factors were age >55 years, male gender, low body mass index (BMI), diabetes, functional dependence, ventilator dependence, history of severe chronic obstructive pulmonary disease, hypertension, systemic sepsis, white blood cell count >12,000, emergency case, American Society of Anesthesiologists class ≥3, general anaesthesia and total surgical time >240 min. Ten featured factors were used in the nomogram (C-statistic=0.803). Postoperative pneumonia was associated with extended hospital stay. Compared with other postoperative complications, pneumonia had the second-highest impact on the extension of hospital stay (by 4.7 days). This study identified several pre-operative risk factors for postoperative pneumonia after craniotomy. Novel factors including male gender and low BMI warrant further investigation. This novel nomogram could serve as a reliable tool to evaluate the risk of postoperative pneumonia pre-operatively.