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

Int J Antimicrob Agents. 2020 Sep;56(3):106110. doi: 10.1016/j.ijantimicag.2020.106110. Epub 2020 Jul 23.


The crude mortality rate in critical pneumonia cases with coronavirus disease 2019 (COVID-19) reaches 49%. This study aimed to test whether levels of blood urea nitrogen (BUN) in combination with D-dimer were predictors of in-hospital mortality in COVID-19 patients. The clinical characteristics of 305 COVID-19 patients were analysed and were compared between the survivor and non-survivor groups. Of the 305 patients, 85 (27.9%) died and 220 (72.1%) were discharged from hospital. Compared with discharged cases, non-survivor cases were older and their BUN and D-dimer levels were significantly higher (P < 0.0001). Least absolute shrinkage and selection operator (LASSO) and multivariable Cox regression analyses identified BUN and D-dimer levels as independent risk factors for poor prognosis. Kaplan-Meier analysis showed that elevated levels of BUN and D-dimer were associated with increased mortality (log-rank, P < 0.0001). The area under the curve for BUN combined with D-dimer was 0.94 (95% CI 0.90-0.97), with a sensitivity of 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 concordance 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/mL appears to identify patients at high risk of in-hospital mortality, therefore it may prove to be a powerful risk assessment tool for severe COVID-19 patients.

Keywords: Blood urea nitrogen; COVID-19; D-dimer; Viral pneumonia.

MeSH terms

  • Aged
  • Area Under Curve
  • Betacoronavirus / pathogenicity*
  • Biomarkers / blood
  • Blood Urea Nitrogen*
  • COVID-19
  • Coronavirus Infections / blood
  • Coronavirus Infections / diagnosis*
  • Coronavirus Infections / mortality*
  • Coronavirus Infections / virology
  • Female
  • Fibrin Fibrinogen Degradation Products / metabolism*
  • Hospital Mortality
  • Humans
  • Male
  • Middle Aged
  • Pandemics
  • Pneumonia, Viral / blood
  • Pneumonia, Viral / diagnosis*
  • Pneumonia, Viral / mortality*
  • Pneumonia, Viral / virology
  • Prognosis
  • Proportional Hazards Models
  • Retrospective Studies
  • Risk
  • SARS-CoV-2


  • Biomarkers
  • Fibrin Fibrinogen Degradation Products
  • fibrin fragment D