Supplementary Material for: Diagnosis value of the blood urea nitrogen to creatinine ratio in determining the need for intervention of acute upper gastrointestinal bleeding

Introduction: The blood urea nitrogen (BUN) to creatinine (Cr) ratio (BUN/Cr ratio) may be used to evaluate the need for intervention of acute upper gastrointestinal bleeding (AUGIB). This study aimed to explore the predictive value of the BUN/Cr ratio in the need for intervention of AUGIB. Methods: This retrospective observational study included patients with AUGIB in the hospital's emergency department between August 2019 and May 2023. The patients were grouped according to whether they underwent an intervention for AUGIB. Patients treated between August 2019 and May 2022 were selected as the training set and the others as the validation set. Results: A total of 466 patients (328 males, 138 females) with AUGIB were enrolled in the intervention group (n=167) and the no-intervention group (n=299). In the training set, multivariable logistic regression showed that the BUN/Cr ratio (OR: 1.013, 95%CI: 1.003-1.023, P=0.009), hemoglobin (OR: 0.989, 95%CI: 0.981-0.997, P=0.010), and a previous history of esophageal variceal bleeding (OR: 6.898, 95%CI: 3.989-11.929, P<0.001) were independently associated with intervention for AUGIB. The area under receiver operating characteristic curve of BUN/Cr ratio and the prediction model based on logistic regression to predict the need for intervention of AUGIB were 0.604 (95%CI: 0.544-0.664) and 0.759 (95%CI: 0.706-0.812) in the training set and 0.634 (95%CI: 0.529, 0.740) and 0.708 (95% CI: 0.609, 0.806) in the validation set, respectively. Conclusion: The BUN/Cr ratio was associated with the need for AUGIB intervention. Combining it with other parameters might improve its diagnostic value to predict the need for intervention of AUGIB.