Abstract
BACKGROUND: Pneumonia, the most common infection following cardiac surgery, is associated with major morbidity and mortality. Although prior work has identified preoperative risk factors for pneumonia, the present study evaluated the role and associated impact of intraoperative and postoperative risk factors on pneumonia after cardiac surgery. METHODS: This observational cohort study evaluated 71,165 patients undergoing coronary and/or aortic valve surgery across 33 institutions between 2011 and 2021. Terciles of estimated pneumonia risk were compared between a validated preoperative model (Model One) and a model additionally accounting for significant intraoperative (eg, bypass duration) and postoperative (eg, extubation time) factors (Model Two). Logistic regression was used to develop and validate Model Two. RESULTS: Postoperative pneumonia occurred in 2.62% of the patients. A total of 9 significant intraoperative and early postoperative risk factors were identified. The absolute risk of pneumonia increased across Model One terciles: low (≤1.04%), medium (1.04%-2.40%), and high (>2.40%). Model two performed well (c-statistic = 0.771). Most patients (60.1%) had no change in their preoperative versus intraoperative/postoperative risk tercile. The 19.6% of patients who increased their risk tercile with Model Two accounted for 18.6% of all pneumonia events. CONCLUSIONS: This study identified 9 significant perioperative risk factors for pneumonia. Nearly 1 of every 5 patients moved into a higher pneumonia risk category based on their intraoperative and postoperative course. These findings may serve as the focus of future quality improvement efforts to reduce a patient's risk of postoperative pneumonia.