Clinical factors associated with in-hospital mortality in elderly versus non-elderly pneumonia patients in the emergency department

BACKGROUND: Pneumonia is a respiratory infection with an increasing incidence with age. However, limited evidence has identified factors associated with its outcome among different age groups, especially in the elderly and in the emergency department (ED) setting. We aimed to identify clinical factors associated with in-hospital mortality in elderly versus non-elderly pneumonia patients in the ED. METHODS: A retrospective observational study was conducted at the ED of Siriraj Hospital, Thailand. Patients aged at least 18 years old diagnosed with non-COVID pneumonia between June 1, 2021, and May 31, 2022, were included. They were categorized into the elderly (age ≥ 65 years) and non-elderly (age < 65 years) groups. The primary outcome was in-hospital mortality. We employed multivariate logistic regression models to identify independent factors associated with the outcome in each age group. RESULTS: We enrolled 735 patients, 515 elderly and 222 non-elderly. There was no difference in in-hospital mortality rate between the two groups (39.0% in the elderly and 32.9% in the non-elderly; p = 0.116). In the elderly cohort, independent factors associated with in-hospital mortality were do-not-resuscitate (DNR) status (adjusted odds ratio (aOR) 12.89; 95% confidence interval (CI) 7.19–23.1; p < 0.001), Glasgow Coma Scale (GCS) score (aOR 0.91; 95%CI 0.85–0.96; p = 0.002), hemoglobin level (aOR 0.9; 95%CI 0.82–0.98; p = 0.012) and the type of initial oxygen support (p = 0.05). Among non-elderly patients, independent factors were DNR status (aOR 6.81; 95%CI 3.18–14.59; p < 0.001), GCS score (aOR 0.89; 95%CI 0.8–0.99; p = 0.025), platelet level (aOR 1; 95%CI 1–1; p = 0.038), Charlson Comorbidity Index (CCI) (aOR 1.12; 95%CI 0.99–1.28; p = 0.078), and the type of initial oxygen support p = 0.079). CONCLUSION: In pneumonia patients presenting to the ED, DNR status, lower GCS score, and more invasive initial oxygen supplementation were independently associated with in-hospital mortality in both elderly and non-elderly groups. However, lower hemoglobin level was only associated with in-hospital mortality in the elderly, while higher CCI and lower platelet count were independent factors only in the non-elderly. These findings emphasize the importance of age-specific considerations for the disease, and these factors are potential prognostic markers that may be used in clinical practice to improve patient outcomes.