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The study of some physiological and biochemical indices as predictive markers of an unfavorable outcome of COVID-19 pneumonia

The study is aimed to determine via mathematical methods the significance of some physiological and biochemical indices as predictive markers of an unfavorable outcome of pneumonia caused by the SARS-CoV-2 virus.
For this purpose a retrospective analysis of the clinical data of the COVID hospital patients was carried out. A random cohort of patients with COVID-19 pneumonia numbered 209 people. In total 15 indices were studied: the physiological characteristics of patients described during hospitalization, the indices of blood coagulation, C-reactive protein (CRP) level, urea and creatinine concentration in blood. The analyzed parameters were categorized relative to the reference intervals of physiologically normal values. Correlation analysis was carried out using categorical data on the disease outcome. The algorithms for calculating statistical characteristics, as well as results visualization, were implemented in the Python language. The significance of differences in signs when comparing patient groups was assessed using the Pearson’s χ2 test with Yates’ correction. The reliability of the results was assessed using one-way analysis of variance using Fisher’s F-test. The studies were carried out in accordance with international and Russian ethical principles and norms.
There were revealed maximal correlation coefficients between the level of blood oxygen saturation (−0.43), as well as the respiratory rate (0.43), and a mortal outcome. For patients over 50 years of age, oxygen saturation below 80% at the time of hospitalization turned out to be a marker of mortality. It was shown that D-dimer blood level above 625 ng/mL and an increase in the concentration of creatinine and urea in the blood by 2.5 times are associated with mortal outcomes of the old patients. No correlation was found between the CRP level and the disease outcome. The effect of corticosteroids on the disease outcome was analyzed in patients with different CRP levels. It was found that while using corticosteroids, the mortality rate in patients with CRP ≤ 12.5 mg/L is 2.7 times higher than in those with CRP > 12.5 mg/L (p < 0.01). Thus, the use of adequate mathematical methods made it possible to define more precisely some mortality-associated indices in patients with COVID-19 pneumonia.