AKI more common, severe in patients with COVID-19 vs influenza
AKI was more common in hospitalizations for COVID-19 than influenza, with study results indicating that AKI with the former led to more severe outcomes, including the need for mechanical ventilation and increased mortality.
For patients who survived at 90 days, rates of kidney function recovery were similar in both groups at 90%.
“Acute kidney injury is a common complication in patients hospitalized with SARSCoV-2 (COVID-19), with prior studies implicating multiple potential mechanisms of injury,” Bethany C. Birkelo, DO, of Vanderbilt Center for Kidney Disease and Integrated Program for Acute Kidney Injury Research, and colleagues wrote. “Although COVID-19 is often compared to other respiratory viral illnesses, few formal comparisons of these viruses on kidney health exist. In this retrospective cohort study, we 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.”
Utilizing electronic medical records, Birkelo and colleagues identified 3,402 hospitalizations for COVID-19 and 3,680 hospitalizations for influenza between October 2019 and May 2020.
“To control for any potential seasonal, temporal, or surge effects in the early pandemic, we performed a sensitivity analysis which adjusted for admission date as a continuous variable with a five-knot spline in the propensity score weighting,” the researchers wrote, further noting that patients in both groups were similar in age, but those hospitalized with COVID-19 were more likely to be African American patients.
AKI in COVID-19 vs influenza
A comparison of AKI incidence between the two conditions showed a higher prevalence of AKI in hospitalizations for COVID-19 than influenza (41% vs. 29%), with the severity of AKI stage also higher in patients with COVID-19.
An analysis of inpatient characteristics revealed differences between groups, with trough oxygen saturations of less than 88% found in 26% of patients with COVID-19 and in 14% of patients with influenza. Patients in the COVID-19 group were more likely to require mechanical ventilation (17% vs. 3%) and to receive vasopressors (13% vs. 2%).
Regarding mortality, researchers observed higher rates of inpatient death (30% vs. 3%) and death at 90 days after peak serum creatinine (35% vs. 9%) for those in the COVID-19 group.
“While this finding highlights the high mortality associated with AKI in COVID-19, it also provides some optimism for recovery in those who survive the illness, as approximately 90% of survivors of non-dialysis-requiring AKI recovered,” the researchers wrote.
Further observations indicated more patients in the COVID-19 group required kidney replacement therapy (13% vs. 2%) and that these patients were also more likely to remain on dialysis at hospital discharge (8% vs. 1%).
AKI burden, resource allocation
“Our findings have important resource implications,” Birkelo and colleagues wrote. “We observed a substantial incidence of AKI in influenza, with one-quarter of patients experiencing AKI during hospitalization. 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 ...
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.”