Diagnostic performance of initial blood urea nitrogen combined with D-Dimer levels for predicting in-hospital mortality in COVID-19 patients

Cheng, Anying; Hu, Liu; Wang, Yiru; Huang, Luyan; Zhao, Lingxi; Zhang, Congcong; Liu, Xiyue; Xu, Ranran; Liu, Feng; Li, Jinping; Ye, Dawei; Wang, Tao; Lv, Yongman; Liu, Qingquan

The crude mortality rate in critical pneumonia cases of the new coronavirus disease (COVID-19) has reached 49%. This study aimed to test whether the levels of blood urea nitrogen (BUN) combined D-Dimer were predictors of in-hospital mortality in COVID-19 patients. We analyzed the clinical characteristics of 305 COVID-19 patients and compared them between the survivor and non-survivor groups. A total of 85 (27.9%) patients died, and 220 (72.1%) patients were discharged. Compared with discharged cases, non-survivor cases were older, and their BUN and D-Dimer levels were significantly higher (P<0.0001). LASSON and multivariable COX regression analyses identified BUN and D-Dimer as independent risk factors for poor prognosis. Kaplan-Meier analysis showed that elevated levels of BUN and D-Dimer had increased mortality compared with the other group (log-rank: P<0.0001). The area under the curve for BUN combined D-Dimer was 0.94 (95% CI 0.90–0.97), with a sensitivity of 0.85 and specificity of 91%. Based on BUN and D-Dimer levels on admission, a nomogram model was developed that showed good discrimination, with a C-index of 0.94. Together, initial BUN and D-Dimer levels were associated with mortality in COVID-19 patients. The combination of BUN>4.6 mmol/L and D-Dimer≥0.845 µg/L appears to identify patients of the high risk of in-hospital mortality; therefore, it may prove to be a powerful risk assessment tool for severe COVID-19 patients.