Half of Patients in Hospital for COVID-19 Get Acute Kidney Injury

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Acute kidney injury (AKI) is a frequent complication among patients hospitalized for COVID-19, with incidence rates of 39% and 52% in two independent, European case series presented recently at the International Society of Nephrology (ISN): 2021 World Congress. Many of the cases progressed to more severe, stage 3 AKI. Factors linked with incident AKI in the two reports included use of mechanical ventilation, vasopressors, or diuretics, and elevations in inflammatory markers.

The new findings confirm several US reports published during the past year. In those reports, roughly a third of patients hospitalized for COVID-19 developed AKI during their hospital stay, said Jay L. Koyner, MD, during another renal conference, the National Kidney Foundation (NKF) 2021 Spring Clinical Meetings.

Experience has shown it's bad news when hospitalized COVID-19 patients develop AKI, which can prove fatal or can lead to the development or worsening of chronic kidney disease (CKD), which in some cases rapidly progresses to end-stage disease.

COVID-19 Giving Nephrologists an Opportunity to Improve AKI Care

"COVID is giving us an opportunity to do a better job of taking care of patients who develop AKI, which is something that nephrologists have not often excelled at doing," said Koyner, professor and director of the nephrology intensive care unit (ICU) at the University of Chicago.

"Many studies will look at how we can manage COVID-19 patients better after they develop AKI, because I suspect a large number of these patients will wind up with CKD," Koyner said during his talk.

He cited several lessons from reports of AKI that occurs in patients hospitalized for COVID-19:

Preexisting CKD, obesity, and severe COVID-19 appear to be risk factors for developing COVID-related AKI.
Patients who develop AKI during acutely severe COVID-19 may have slightly worse outcomes than patients without COVID-19 who develop AKI.
Certain genetic susceptibilities may play a role in developing COVID-19-related AKI.
Routine follow-up of AKI is generally inadequate and is not standardized, whether AKI develops while ill with COVID-19 or in other settings.

The most encouraging AKI take-away from COVID-19's first year is that its incidence among patients hospitalized with COVID-19 appears to have dropped from very high rates early on, possibly because of more routine use of steroids for critically ill patients with COVID-19 and a reduction in the use of ventilators, Koyner suggests.

In-Hospital Diuretic Treatment Links With AKI

One of the World Congress of Nephrology reports involved 1248 patients admitted with confirmed COVID-19 at two tertiary-care hospitals in London during March–May 2020. The average age of the patients was 69 years, 59% were men, and 17% had CKD at admission, as determined on the basis of estimated glomerular filtration rate <60 mL/min/1.73 m².

During hospitalization, 487 patients (39%) developed AKI, including 175 (14%) with stage 3 AKI and 109 (9%) who required renal replacement therapy (dialysis or kidney transplant). The incidence of AKI peaked 5 weeks after COVID-19 admission, reported Paul Jewell and his associates from King's College Hospital, London, United Kingdom, in a poster.

Multivariate analysis identified several demographic and clinical variables that were significantly linked with an increased risk of developing AKI: male sex (which boosted risk by 55%), Black race (79% higher risk), CKD at admission (triple the risk), being hypertensive on admission (73% higher risk), and being administered diuretics during hospitalization (69% higher risk).

The findings of a risk linked with diuretic use "supports the cautious use of diuretics in patients hospitalized with COVID-19, especially in the presence of background renal impairment," the authors said.

For patients with incident AKI, the 30-day mortality rate was significantly increased; mortality was 59% higher among patients who developed stage 1 AKI and was roughly triple among patients who developed stage 2 or 3 AKI.

Second Report Links Ventilation, Vasopressors With Worse AKI

A separate report from clinicians at Charité Hospital, Berlin, Germany, retrospectively reviewed 223 patients admitted with symptomatic COVID-19 to three Charité sites during March–June 2020. During hospitalization, 117 patients (52%) developed AKI, including 70 (31%) with stage 3 disease; 67 (30%) required renal replacement therapy. Half the patients with stage 3 AKI required ICU admission.

Compared with patients with less severe AKI, patients who developed stage 3 AKI were more often male, older, and had a higher body mass index.

In a multivariate model, compared with patients who developed less severe AKI, those who developed stage 3 disease also were significantly more likely to have received mechanical ventilation or vasopressor drugs and were more likely to have increased levels of leukocytes or procalcitonin, two inflammatory markers, reported Jan-Hendrink B. Hardenburg, MD, a Charité nephrologist, and his associates in a poster at the meeting.

Mechanical ventilation was linked with a sixfold higher rate of stage 3 AKI, and treatment with vasopressor drugs was linked with a threefold higher rate. Elevations in procalcitonin or leukocyte levels were linked with about 60% increases in rates of stage 3 AKI. For both of these risk factors, temporal relationships were tighter; increases in both values appeared just before onset of stage 3 disease.

Joyner has been a speaker on behalf of NXStage Medical, a consultant to Astute Medical, Baxter, Mallinckrodt, Pfizer, and Sphingotec, and he has received research funding from Astute, Bioporto, NxStage, and Satellite Healthcare. Jewell and Hardenburg have disclosed no relevant financial relationships.

International Society of Nephrology (ISN): 2021 World Congress: Abstracts POS-027 and POS-029. Presented April 16, 2021.

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