Expert discusses AKI incidence, now on a ‘downward trend,’ in COVID-19 hospitalizations
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A speaker at the virtual Innovations in Dialysis: Expediting Advances Symposium discussed the high incidence of AKI among patients hospitalized with COVID-19 and speculated on why these rates differ across studies.
Further, David E. Leaf, MD, MMSc, FASN, who serves as director of clinical and translational research in AKI in the division of renal medicine at Brigham and Women’s Hospital and assistant professor of medicine at Harvard Medical School, pointed to evidence that suggests AKI is declining in these hospitalizations due to reasons that are not yet thoroughly understood.
AKI across COVID-19 severity
“The incidence of AKI has varied widely among studies, and this variation is largely driven by differences in the severity of illness of the patients in the various studies,” Leaf said during his presentation, noting differences in the percentage of patients who are critically ill and treated in the ICU, as well as in the percentage of patients who require invasive mechanical ventilation or vasopressors.
“And, to a lesser extent, the difference is also driven in variations in the way AKI is defined across studies,” he said.
Despite differences in study design and populations which could impact how researchers determine the prevalence of AKI, Leaf contended the condition is common, especially when investigations include patients with more severe forms of COVID-19.
“A recently published meta-analysis that included 20 studies and roughly 13,000 hospitalized patients with COVID-19 found that the incidence of AKI was 17%, or roughly one in six hospitalized patients. The incidence of AKI requiring dialysis, which is of course the most severe form of AKI, was roughly 5%,” he said. “That’s all patients that are admitted to the hospital with COVID-19: What about when we just focus on the sickest patients, those that are admitted to the ICU?”
Here, Leaf cited a multicenter cohort study, for which he served as the principal investigator. That study, known as Study of the Treatment and Outcomes in Critically Ill Patients With COVID-19 (STOP-COVID), included 5,000 critically ill adult patients admitted to ICUs at 68 hospitals across the United States. According to Leaf, findings demonstrated an overall AKI incidence of 50%, as well as a 20% incidence of AKI requiring dialysis.
AKI in hospitalizations for COVID-19 vs. unrelated causes
“Now, putting these numbers into perspective, one of the questions that comes up is whether these are higher rates of AKI than you would see in similarly ill hospitalized patients without COVID-19,” Leaf said.
Two studies, which compared AKI in patients with and those without COVID-19, confirmed that patients who acquire the infection are more likely to develop AKI than “contemporaneous” patients without COVID-19. Specifically, a study of more than 20,000 patients hospitalized within the Yale medical system showed COVID-19 was independently associated with a 40% higher risk for AKI (90% of the study population were hospitalized for reasons other than COVID-19), while another study from Montefiore estimated a 50% increased risk.
Why AKI incidence may be declining
“The last thing I’ll say about incidence is that rates of AKI in hospitalized patients with COVID-19 appear to be declining over time,” Leaf said. “I can say this anecdotally, having just been in service in the ICU the other week and having spoken with colleagues at other hospitals, but there have also been studies that have documented this downward trend in AKI.”
While the reasons for this remain unclear, Leaf said improved therapeutics (such as dexamethasone and tocilizumab) may play a role. In addition, patients hospitalized with COVID-19 at this point in time tend to be younger (and unvaccinated) and so, according to Leaf, they are less likely to have underlying chronic kidney disease and other traditional AKI risk factors.
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Leaf DE. Panel session I: COVID-19 and the kidney. Presented at: Innovations in Dialysis: Expediting Advances Symposium; Aug. 22-24, 2021 (virtual meeting).
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