Prognostic value of serum albumin and urea nitrogen excretion in COVID-19 ICU patients: a single-center, prospective, cohort study

Introduction. Catabolic syndrome is typical for most critical illness situations. A long progressive course of hypercatabolism is considered by a number of authors as a prognostic criterion for negative clinical outcome of the disease. Objective. Evaluation of the prognostic value of some indicators of the severity of catabolic syndrome in ICU patients with COVID-19. Materials and methods. A prospective cohort study was conducted in 55 patients of the intensive care unit in the period from May 2020 to March 2021. The severity of hypercatabolism was determined by the dynamics of serum albumin and daily urinary nitrogen excretion within 14 days from admission to the ICU. Comparative analysis of nonparametric quantitative data was carried out using the Mann-Whitney test. To determine the predictive value of the diagnostic test, we plotted using the curves of operating characteristics (ROC, Receiver Operating Characteristics) with the subsequent determination of the sensitivity and specificity at the separation point. Results. ROC analysis revealed moderate sensitivity (75.9 %) and low specificity (58.1 %) of the daily urinary nitrogen excretion during the first 14 days of treatment in the ICU in patients with severe SARS-CoV-2. It was also shown that the dynamics of serum albumin has a low predictive value for negative clinical outcome. It should be noted that in the group of survived patients a significant increase in daily urinary nitrogen excretion was observed on days 4-7 (p = 0.022) and 8-14 (p = 0.01) of intensive therapy. Conclusions. Nitrogen urinary excretion is a more accurate prognostic marker of poor clinical outcome than serum albumin in ICU patients with COVID-19. The main feature of the catabolic syndrome in patients with positive clinical outcome is a progressive increase in the rate of urinary nitrogen excretion from 4 to 14 days after admission to ICU.