NASHVILLE, TN — COVID-19 is often compared to other respiratory viral illnesses, but few of those comparisons contrast the virus’ varying effect on kidney health and function.
That is the case even though acute kidney injury is a common complication in patients hospitalized with SARS-CoV-2 (COVID-19), suspected of being caused by multiple potential mechanisms of injury.
A retrospective cohort study published Kidney International compared the incidence, features and outcomes of acute kidney injury among veterans hospitalized with COVID-19 or influenza and adjusted for baseline conditions using weighted comparisons.1
Using electronic medical records, researchers from the VA Tennessee Valley Healthcare System and Vanderbilt University looked at 3,402 hospitalizations for COVID-19 and 3,680 hospitalizations for influenza admitted between Oct. 1, 2019 and May 31, 2020 across 127 VA hospitals nationally.
Results demonstrated that acute kidney injury occurred more frequently among those with COVID-19 compared to those with influenza (40.9% vs. 29.4%, weighted analysis) and was more severe.
In addition, COVID-19 patients were more likely to require mechanical ventilation and vasopressors and experienced higher mortality. While frequent in both groups, proteinuria and hematuria were more common in COVID-19. Recovery of kidney function was less common in patients with COVID-19 and acute kidney injury but was similar among survivors.
“Thus, findings from this study confirm that acute kidney injury is more common and severe among patients hospitalized with COVID-19 compared to influenza, a finding that may be driven largely by illness severity,” researchers wrote. “Hence, the combined impact of these two illnesses on kidney health may be significant and have important implications for resource allocation.”
The authors advised that in-hospital mortality was higher and kidney recovery was lower among hospitalized patients with COVID-19 compared with influenza, although similar among survivors.
Essentially, the study underscored that incidence and severity of AKI in COVID-19 differ from those in patients with other severe viral respiratory illness, even after adjusting for premorbid demographics and disease. “We found that AKI occurred more frequently and was more severe among those with COVID-19,” researchers explained. “The difference in AKI incidence persisted even after adjusting for baseline characteristics, suggesting that the higher rate of AKI in COVID-19 was not explained by comorbid conditions. We also observed that patients with COVID-19 were more likely to require mechanical ventilation and vasopressors and had higher in-hospital mortality than those with influenza, suggesting that higher severity of illness is likely an important contributor to these differences. These findings are consistent with a recent, smaller study that found similar rates of AKI in COVID-19 and influenza among critically ill patients with similar illness severity.”
The authors pointed out that their findings have important resource implications. “We observed a substantial incidence of AKI in influenza, with one-quarter of patients experiencing AKI during hospitalization,” they wrote. “It remains to be seen what the impact of mask wearing and social distancing will have on incidence of influenza in the current and future influenza seasons. Regardless, the potential added burden of AKI related to influenza in addition to AKI during hospitalization with COVID-19 could have downstream implications for resource utilization.”
Researchers added, “Given the strain on the health system due to COVID-19, the overall increased burden of kidney disease and its resource allocation due to these illnesses will be important to project. The proportion of patients with AKI who remain dialysis dependent at discharge in our study suggests that this strain on resources may extend to outpatient dialysis centers.”
They concluded, “The relatively high incidence of AKI in both illnesses provides important information on the anticipated burden on the kidney health of veterans, and similarly ill populations and their care providers.”
- Birkelo BC, Parr SK, Perkins AM, Greevy RA Jr, et. al. Comparison of COVID-19 versus influenza on the incidence, features, and recovery from acute kidney injury in hospitalized United States Veterans. Kidney Int. 2021 Oct;100(4):894-905. doi: 10.1016/j.kint.2021.05.029. Epub 2021 Jun 7. PMID: 34111501; PMCID: PMC8183091.