The Incidence of Acute Kidney Injury (AKI) in Critically Ill COVID-19 Patients: A Single-Center Retrospective Cohort Study at a Tertiary Level Hospital in Oman.

Background:  Acute kidney injury (AKI) is associated with adverse outcomes in critically ill patients. Coronavirus disease 2019 (COVID-19) affects the renal system frequently and leads to AKI. This study aims to determine the incidence of AKI, risk factors including hyperglycemia, and the requirement for renal dialysis.

Methods:  A retrospectively observational study was done at Sultan Qaboos University Hospital between March 2020 and September 2021. A total of 286 adult patients with laboratory-confirmed COVID-19 infection admitted to the intensive care unit (ICU) were included in the study. The patient's medical records were reviewed. Patients' baseline demographic characteristics, APACHE score on admission, clinical data including length of stay, oxygenation parameters, ventilator days, shock, AKI (KIDIGO guideline), dialysis, medications, lab on admission as well as during the ICU stay, and the outcome (mortality) were recorded in detail. Follow-up was done till discharge from ICU.

Results:  The study population included 68.5% (196/286) males. The median age was 56 years (interquartile range, IQR: 43-66.25). The incidence of AKI was 55.2% (158/286) overall. Out of those who had AKI, 27.2% (43/158), 31.6% (50/158), and 41.1% (65/158) developed AKI stages 1, 2, and 3, respectively. Univariate analysis for the development of AKI showed the following significant variables: age (p=0.005; odds ratio, OR 1.024; 95% confidence interval, CI 1.007-1.041), creatinine level on admission (p=0.012; OR 1.005; 95%CI 1.001-1.008), APACHE score on admission (p<0.001; OR 1.049; 95%CI 1.021-1.077), P/F ratio (p<0.001; OR 0.991; 95%CI 0.987-0.995), nephrotoxic agent (p<0.001; OR 8.556; 95%CI 4.733-15.467), shock (p<0.001; OR 8.690; 95%CI 5.087-14.843), days on the ventilator (p<0.001; OR 1.085; 95%CI 1.043-1.129), and length of stay in ICU (p<0.001; OR 1.082; 95%CI 1.047-1.119). The multivariate analysis confirmed only shock (p=0.004; OR 5.893; 95%CI 1.766-19.664). A total of 41.7% (66/158) of patients received dialysis. Hyperglycemia was not associated with the development of AKI. For patients with AKI, those having high APACHE score (p<0.001), shock (p=0.56; OR 2.326; 95%CI 1.036-5.223), ischemic heart disease (IHD) (p=0.002; OR 9.000; 95%CI 1.923-42.130), and hypertension (p=0.023; OR 2.145; 95%CI 11.125-4.090) were significantly associated with the requirement of dialysis. The mortality was found to be 59.1% (169/286) overall whereas it was 83.5% (132/158) for AKI versus 28.9% (37/158) for non-AKI cases.

Conclusions:  A high incidence of AKI for critically ill COVID-19 cases was found in this study. The shock was the only significant predictor for the development of AKI. AKI is associated with high mortality in these patients.