Value of the urea-to-creatinine ratio for predicting mortality in pneumonia: a retrospective study with propensity score matching

Aims: This study aimed to evaluate the prognostic value of the urea-to-creatinine ratio (UCR) in predicting in-hospital mortality among patients diagnosed with pneumonia and to compare its performance with the neutrophil-to-lymphocyte ratio (NLR), while minimizing confounding factors by propensity score matching. Methods: This retrospective, single-center observational study included adult patients with clinically and radiologically confirmed pneumonia who presented to the emergency department between 2023 and 2025. Demographic characteristics, laboratory parameters, and clinical outcomes were obtained from the hospital’s electronic medical record system. UCR and NLR were calculated using laboratory values recorded at admission. Receiver operating characteristic (ROC) curve analyses were performed both before and after 1:1 nearest-neighbor propensity score matching, which was conducted using age, troponin I, and pro-BNP as matching variables. The primary outcome was all-cause in-hospital mortality. Results: A total of 2,884 patients met the inclusion criteria. Non-survivors (n=442) showed significantly higher UCR and NLR levels compared with survivors (n=2,442; p