Association Between an Increase in Blood Urea Nitrogen at 24 Hours and Worse Outcomes in COVID-19 Pneumonia (preprint)

ABSTRACT

Background and objectives: The dynamic change of blood urea nitrogen (BUN) have been proved to be related to the worse outcomes in various diseases such as pulmonary embolism, acute pancreatitis and acute nonvariceal upper GI bleeding. In the present study, we aimed to identify the association between blood urea nitrogen (BUN) change and clinical outcomes in patients presenting with COVID-19 pneumonia.Methods: This is a retrospective study conducted in the Huoshenshan hospital. Patients with laboratory-confirmed COVID-19 from Feb 5th to March 5th in 2020 who had BUN level tested on admission and on the second day consecutively were included. Patients were stratified into two groups according to the BUN change (increase vs. no increase) during the first 24 hours. The primary outcome was in-hospital mortality. Moreover, other clinical outcomes were also compared. The potential risk factors of in-hospital mortality were analyzed. Results: There were 266 patients included in the study. The mean change in BUN at 24 hours was 1.0 mg/dL, with 206 patients (77.4%) experiencing no increase in BUN and 60 patients (22.6%) experiencing an increase in BUN. In-hospital mortality was significantly higher in the BUN increase group compared to no increase group (30.0% vs. 5.8%, P<0.001). BUN increase group also had higher requirement for ICU admission, use of invasive mechanical ventilation and incidence of AKI (all P<0.001). After adjusted for related factors, the BUN increase was independently associated with the mortality with an odds ratio of 7.427[95% CI 2.370-23.279]. In the multivariable and survival analysis, BUN increase was also found to be associated with survival regardless of the admission BUN.Conclusions: In patients with COVID-19, BUN increase at 24 hours was an independent predictor for a composite clinical outcome and in-hospital mortality. The association of BUN increase with worse outcomes further emphasizes the importance of monitoring BUN change and kidney function in the course of COVID-19.