Kidney Dysfunction And COVID-19: Characteristics, Predictive Factors, And Influence Of Age

Background: COVID-19 severity and mortality are strongly influenced by age and comorbidities. Among comorbidities, kidney dysfunction seems to play a crucial role. Indeed, acute kidney injury (AKI) is a frequent finding in hospitalized COVID-19 patients and seems to be associated to mortality and severity. On the other hand, the role of chronic kidney disease (CKD) in COVID-19 is more debated. Aims: and Methods We performed a retrospective study in a cohort of 174 hospitalized COVID-19 patients in Italy from March 3 rd to May 21 st 2020, to investigate the role of kidney dysfunction on COVID-19 severity and mortality. Moreover, we examined in depth the relationship between kidney function, age, and progression of COVID-19, also using different equations to estimate the glomerular filtration rate (GFR). Hazard ratios (HR) and odds ratios (OR) were obtained by logistic regression, while a predictive analysis was made through a machine learning approach. Results: AKI and death occurred in 10.2 % and 19.5% respectively, in our population. Serum creatinine, blood urea nitrogen, neutrophils, lymphocytes, c-reactive protein and procalcitonin were significantly correlated to mortality and severity of the disease. The major risk factors for mortality in our cohort were age [adjusted HR, 6.2; 95% confidence interval (CI) 1.8-21.4] and AKI [3.36 (1.44-7.87)], while, in these relationships, GFR at the baseline mitigated the role of age. The occurrence of AKI was influenced by baseline kidney function, D-dimer and procalcitonin and hypertension. Our predictive analysis for AKI and mortality reached an accuracy ≥ of 94% and 91%, respectively. In patients ≥ 70 years, MDRD and CKD-EPI showed a better performance in the prediction of AKI and mortality, compared to BIS-1 formula. Discussion: Our study confirms the importance of AKI as a risk factor in COVID-19 disease, while it scales down the role of CKD, especially in elderly patients. BIS-1 formula demonstrated a worse performance to predict the outcomes in COVID-19 patients when compared to MDRD and CKD-EPI.