Risk factors and outcomes of postoperative aspiration pneumonia in abdominal surgery patients: An exact matching and weighting analysis

Abstract

Background: Postoperative aspiration pneumonia is a feared complication contributing significantly to postoperative morbidity and mortality. Over decades, there has been little progress in reducing incidence and mortality of postoperative aspiration pneumonia. Here, we assessed risk factors for postoperative aspiration pneumonia in general and abdominal surgery patients.

Methods: Patients undergoing surgery between January 2012 and December 2018 were included in this exact matched and weighted case-control study. Data from a prospectively acquired clinical database were retrospectively analyzed.

Results: Among 23,647 patients undergoing 32,901 operations, 144 (0.44%, 95% Confidence Interval: 0.37%-0.52%) cases of postoperative aspiration pneumonia were identified. Ninety-day mortality was 27.8% (n = 40). Major risk factors for postoperative aspiration pneumonia were emergency surgery in patients with prolonged preoperative fasting (>6 hours; odds ratio: 3.25, 95% confidence interval: 1.46-7.26; P < .001), older age with increasing risk in octogenarians compared to seniors (65-80 years: n = 69; odds ratio 5.23, 95% confidence interval: 2.18-12.51; >80 years: n = 50; odds ratio 13.72, 95% confidence interval: 4.94-38.09; P < .001), American Society of Anesthesiologists scores >II (American Society of Anesthesiologists III: n = 90; odds ratio 3.38, 95% confidence interval: 1.08-16.01; American Society of Anesthesiologists IV/V: n = 18; odds ratio 5.20, 95% confidence interval: 1.48-27.61; P < .001), and body mass index <18 kg/m² (n = 9; odds ratio: 2.53; 95% confidence interval: 1.04-6.11; P = .029). Laparoscopies (odds ratio 0.45, 95% confidence interval: 0.23-0.88; <0.001) and female sex were associated with a decreased risk for postoperative aspiration pneumonia (odds ratio 0.40, 95% confidence interval: 0.23-0.69; P < .001).

Conclusion: Preventive measures to reduce postoperative aspiration pneumonia should focus on older patients with American Society of Anesthesiologists scores ≥III undergoing open surgery. Cachectic patients and patients undergoing emergency surgery with prolonged preoperative fasting require increased attention. Laparoscopy was associated with a lower risk for postoperative aspiration pneumonia and should be preferred whenever appropriate.