Incidence of Acute Kidney Injury in Covid-19

Acute kidney injury (AKI) in Covid-19 patients is a topic that receives little attention in the literature, although being important in clinical practice in the ICU, particularly in Oman. Our objective was to determine the incidence of AKI, risk factors, and the requirement of renal replacement treatment.

Methods: All adult patients hospitalized at Sultan Qaboos University Hospital in the critical care unit (ICU) between March 2020 and September 2021 with laboratory-confirmed Covid-19 had their medical records retrospectively reviewed. All patient characteristics, their course of events, and the treatment received in ICU were noted.

The incidence of AKI, its association with the glycemic index, and other possible risk factors will be studied. Those requiring renal replacement therapy will be studied in terms of its predictors and outcomes.

Throughout the world, Coronavirus disease 2019 (COVID-19) is spreading as a pandemic disease. Asymptomatic viral carriers to critically ill patients are found to be affected by Covid-19, which has diverse clinical manifestations. There have been an increase in hospitalizations, respiratory failure, and intensive care unit (ICU) admissions due to this disease.

It has been reported that acute kidney injury (AKI) is a common complication of COVID-19 that is associated with a higher mortality rate. It has been reported that AKI in patients with COVID-19 infection ranges from 6.5% to 46% \[3\], with the highest rates among critically ill patients (23%-81%\]. Different definitions of AKI and different populations have resulted in different incidences of AKI.

Several factors have been suggested as contributing to the development of AKI in patients with COVID-19: immunologic injury associated with inflammatory response, direct cytotoxicity over endothelial and tubulo-epithelial cells and podocytes, microthrombi and thrombotic microangiopathy, or cardiorenal syndrome due to right ventricular failure may be present.

There are limited studies in the middle east, especially in Oman, investigating the incidence of AKI in critically ill COVID-19 patients. The aim of this study is to investigate the incidence of AKI, the possible predictive factors for its occurrence in critically ill COVID-19 patients, and the requirement of renal replacement therapy (RRT).

This is a retrospective cohort study carried out in the University hospital in Oman, Sultan Qaboos University Hospital (SQUH), between March 2020 to September 2021. All adult patients admitted to ICU with laboratory-confirmed SARS-CoV-2 infection, documented by real-time RT-PCR on nasopharyngeal swabs, or lower respiratory tract aspirates were included.

Patients with the pre-existing renal disease with eGFR\< 30 or on dialysis and insufficient clinical documentation available for review were excluded. Data was obtained from SQUH "Track Care" hospital information system.

Sample size The sample size was estimated based on the expected incidence proportion of AKI among COVD-19 patients. A recently published systematic review has reported a pooled incidence proportion of 19.45% (95% CI: 14.63 - 24.77)\[5\]. Therefore, the estimated sample size is based on an expected incidence proportion of 20%, a margin of error of 5%, and a confidence level of 95%. The estimated sample size was 250.

Definition of acute kidney injury Kidney Disease Improving Global Outcomes (KDIGO) criteria were used for AKI diagnosis and stratification: stage 1 - increase in serum creatinine from 0.3 mg/dL in 48 hours or increase from 1.5 to 1.9 value of baseline serum creatinine within 7 days; stage 2 - 2 to 2.9-fold increase in serum creatinine within 7 days or urine output below 0.5 mL/kg/h for more than 12 hours; and stage 3 - 3-fold increase in serum creatinine in 7 days or creatinine higher than 4 mg/dL or the initiation of renal replacement therapy through hemodialysis or urine output below 0.3 mL/kg/h for 24 hours or more, or anuria for 12 hours or more. On admission to the ICU, the level of creatinine was measured as a baseline.

Data collection:

To describe the population's characteristics, The following data were used: age, sex, BMI (kg/m2), hypertension (HTN), diabetes mellitus (DM), lung illness (asthma, COPD), cardiovascular disease, chronic kidney disease, onset, length of ICU stay, ventilator days, shock, nephrotoxic agents, the patient medications for DM and details of renal replacement therapy.

Laboratory tests were collected upon admission to the ICU, including PF ratio, full blood count, inflammatory markers (C-reactive protein, IL-6, and ferritin), blood sugar level, D-dimer, and Electrolytes.

All data will be entered into an Excel file and kept under lock. The patient's identity was coded and the complete data file was shared with the statistician.

Eligibility Criteria:
Inclusion Criteria:

* All adult, admitted patients of Covid-19/SARS-2 between March 2020 to September 2021 at Sultan Qaboos University Hospital

Exclusion Criteria:

* Patients with missing data or transferred to another hospital.
* The patients with chronic kidney disease and an estimated glomerular filtration rate (eGFR) of less than 30 mL/min/1.73m², or who underwent renal replacement therapy prior to admission