Huang D, Yang H, Yu H, et al. - The results indicated that for critical illness of COVID-19, increased blood urea nitrogen to serum albumin ratio (BAR) at admission is an independent risk factor. The data showed that a novel predictive nomogram including BAR has superior predictive performance.

• Researchers conducted a retrospective, multicenter, observational study including a sum of 1,370 patients with COVID-19, and 113 (8.2%) patients eventually developed a critical illness in the study.

• The independent risk factors for critical illness included baseline age (OR: 1.031, 95% CI: 1.014, 1.049), respiratory rate (OR: 1.063, 95% CI: 1.009, 1.120), unconsciousness (OR: 40.078, 95% CI: 5.992, 268.061), lymphocyte counts (OR: 0.352, 95% CI: 0.204, 0.607), total bilirubin (OR: 1.030, 95% CI: 1.001, 1.060) and BAR (OR: 1.319, 95% CI: 1.183, 1.471).

• As per the results, 0.821 (95% CI: 0.784, 0.858; P< 0.01) was the predictive AUC of BAR, and the optimal cut-off value of BAR was 3.7887 mg/g (sensitivity: 0.690, specificity: 0.786; positive predictive value: 0.225, negative predictive value: 0.966; positive likelihood ratio: 3.226, negative likelihood ratio: 0.394).

• It was shown that 0.9031125 was the C index of the nomogram including the above six predictors (95% CI: 0.8720542, 0.9341708).