Acute Kidney Injury Associated with Coronavirus Disease 2019 - One Year Later, What Do We Know So Far?

Initial reports early on in the pandemic in 2020 indicate a high incidence of acute kidney injury (AKI) in coronavirus disease 2019 (COVID-19). There is a need to better understand risk factors for AKI in patients with COVID-19. It is also unclear if AKI in patients with COVID-19 differs from AKI due to other causes. More data are required to clarify if COVID-19 is an independent risk factor for AKI and how COVID-19-associated AKI may differ from AKI due to other causes. We, therefore, sought to review the published evidence about the reported relationship between COVID-19, AKI, and outcomes. We performed a systematic search via PubMed and EMBASE using key words "COVID-19" and "AKI" to identify relevant observational studies, case series, and cohort studies published between March 2020 and April 2021. We also manually examined the reference lists of included studies and reviewed the AKI reports published in general medicine journals such as BMJ, Lancet, NEJM, and JAMA. The prevalence of AKI in hospitalized patients with COVID-19 differed across various regions of the world. Initial reports from China where cases of COVID-19 began initially have shown a much lower prevalence compared to those from Europe and North America, especially in critically ill patients in the intensive care unit with acute respiratory distress syndrome. The various components of severe acute respiratory syndrome-associated AKI appear in large parts to be similar to sepsis-induced AKI. However, affinity of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) specifically to the angiotensin-converting enzyme 2 receptors located on podocytes and endothelial cells of the kidney also points toward the direct cytotoxic effects of the virus on the kidney. Numerous mechanisms likely occur simultaneously and hence more treatment approaches need to be streamlined based on pathophysiology. Although data from published literature regarding previous SARS coronaviruses can give some useful insights, we will know more going forward about the nature of kidney injury associated with COVID-19 virus as well as optimum-specific therapeutic management.