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Acute Kidney Injury (AKI) is a frequent complication of hospitalized patients with the disease caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (COVID-19). The impact of COVID-19 in Intensive Care Units (ICU) has been dramatic. We have recently disclosed in an exploratory study a 24.2% mortality rate in critically ill patients with AKI without COVID-19 in our ICU. Reports of the occurrence of AKI and AKI related mortality in patients with COVID-19 have been quite inconsistent. Therefore, the aim of the present study was to evaluate the incidence of AKI in critically ill patients with COVID-19 and assess the association between AKI stage and patient mortality in our hospital.
A retrospective cohort study carried out in 2021 in the Intensive Care Unit of a Brazilian hospital. Patients ≥ 18 years old with COVID-19, hospitalized for ≥ 24 hours, were included, and those on chronic dialysis or diagnosed with brain death were excluded. Data were retrieved from electronic medical records. AKI was defined and classified using serum creatinine (sCr) KDIGO 2012 criteria: increase in sCr by 0.3 mg/dl within 48 hours; or increase in sCr to 1.5 times baseline, which is known or presumed to have occurred within the prior 7 days. Staging of AKI in 3 stages was defined as follows: KDIGO 1- increase in sCr in 1.5–1.9 times baseline OR 0.3 mg/dl increase; KDIGO 2 - increase in sCr in 2.0–2.9 times baseline; KDIGO 3 - increase in sCr in 3.0 times baseline OR increase in sCr to at least 4.0 mg/dl OR initiation of renal replacement therapy. Binomial logistic regression was used to evaluate the impact of baseline sCr on the risk of AKI development. The study was approved by the University Ethics Committee (No. 5,715,083).
A total of 102 patients admitted to ICU with COVID-19 were evaluated. The mean age was 61 years (±14.6). Most were men n=52 (51%), caucasian n=96 (94.1%), elderly n=60 (58.8%), and had hypertension n=60 (58.8%), diabetes n=32 (31.4%) and obesity n=61 (59.8%). The mean body mass index was 30.5 Kg/m2(±5.3), so stage I obesity. Table 1 shows clinical characteristics of patients. AKI was diagnosed in 75 (73.5%) patients. KDIGO stage 3 was the most frequent: 33 (44%), followed by stage 1: 30 (40%). A total of 59 patients died, and AKI was present in 50 of the deceased patients, 26 of which were KDIGO stage 3. Most patients without AKI survived: 18 (66.7%), as shown in Table 2. AKI severity was strongly associated with mortality (Figure 1), particularly in stage 3, which had a death rate of 78.8%. Binomial logistic regression disclosed that higher baseline sCr on hospital admission had a significant adjusted odds ratio of 5.93 (95% CI 1.40-25.17, p=0.016) for the development of AKI, with a predictive accuracy of 72% and a sensitivity of 91.5%, but a specificity of 24.1%. The area under the curve was 0.776.
A high incidence of AKI was observed in critically ill patients with COVID-19, and there is a strong association between AKI staging and mortality in our hospital. Baseline creatinine is a significant predictor of AKI in ICU patients with COVID-19, regardless of age, presence of chronic kidney disease, diabetes, or obesity. The relevance of the present study is explained by a recent increase in COVID-19 diagnosis in Brazil, and the resulting increase in mortality.