Air leakage is a strong risk factor for pneumonia-related acute respiratory distress syndrome.

Background: The number of patients presenting to emergency departments because of pneumonia is gradually increasing. Acute respiratory distress syndrome (ARDS), a serious complication of pneumonia, is associated with high mortality rates, making its early identification crucial. We therefore conducted a retrospective analysis of patients admitted to our emergency department with pneumonia, aiming to screen for clinical factors associated with the development of ARDS. Methods: This was a retrospective study of patients admitted to the emergency department of a hospital in Beijing because of pneumonia from 1 January 2015 to 30 July 2021. Baseline characteristics, comorbidities, complications, etiological information, and imaging findings were collected. Least absolute shrinkage and selection operator (LASSO) regression was used to screen for factors associated with the development of ARDS, and logistic regression was used to fit a nomogram model. Results: The study cohort comprised 1,544 patients, 769 (49.8%) of whom developed ARDS, including 667 (43.2%) men of average age 64.4±18.5 years. These patients were allocated to a training group of 1,080 patients and a test group of 464 patients. Independent risk factors for ARDS were found to be as follows: hemoglobin concentration [odds ratio (OR) 1.01; 95% confidence interval (CI): 1.00, 1.01; P=0.002], vasopressor administered (OR 2.16; 95% CI: 1.57, 2.99; P<0.001), extended-spectrum beta-lactamase (ESBL)-positive Klebsiella pneumoniae (OR 4.37; 95% CI: 1.46, 13.13; P=0.008), Acinetobacter baumannii (OR 3.85; 95% CI: 2.58, 5.74; P<0.001), cytomegalovirus (OR 2.10; 95% CI: 1.33, 3.33; P=0.002), Epstein-Barr virus (OR 2.02; 95% CI: 1.21, 3.35; P=0.007), smoking (OR 1.39; 95% CI: 1.03, 1.89; P=0.03), pneumonia severity index (PSI) grading (OR 2.71; 95% CI: 1.74, 4.21; P<0.001), and evidence of air leakage (OR 5.42; 95% CI: 1.12, 26.23; P=0.04). Age (OR 0.98; 95% CI: 0.97, 0.99; P<0.001), immunosuppressants administered (OR 0.40; 95% CI: 0.17, 0.91; P=0.03), and solid tumors (OR 0.45; 95% CI: 0.27, 0.76; P=0.002) were recognized as protective factors. The area under the receiver operating characteristic (ROC) curve was 0.786 in the training cohort and 0.784 in the test group. Conclusions: Hemoglobin concentration, vasopressor use, ESBL-positive K. pneumoniae, A. baumannii, cytomegalovirus, Epstein-Barr virus, solid tumors, immunosuppressant use, smoking, PSI score, and evidence of air leakage manifestations are independent risk factors for ARDS. Age, immunosuppressants administered and solid tumors are protective factors. Early air leakage is strongly associated with ARDS.