More Than One-Third of Hospitalized COVID-19 Patients Develop AKI, Study Finds

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More than one-third of patients hospitalized for COVID-19 in a large metropolitan New York heath system developed acute kidney injury (AKI), according to a study published in Kidney International (1).

The largest study to date on the incidence of AKI in the United States, the study included 5449 adults admitted with COVID-19 to one of 13 hospitals in the Northwell Health system and found that 36.6% of the patients experienced a kidney injury. There was also a strong relationship between kidney injury and respiratory failure, noted study co-author Jia Hwei Ng, MD, Assistant Professor of Medicine at the Zucker School of Medicine at Hofstra University Northwell Health in Great Neck, New York. About 90% of patients who required mechanical ventilation developed AKI and most of these injuries happened within a day of intubation.

“This gives us some insight that as soon as the patient is admitted with COVID, we have to watch really closely,” Ng said. She also recommended taking note of their volume status and not being afraid to give fluid. Furthermore, many patients with AKI had lower volumes based on urine data, possibly because many had already had fevers for several days. Patients taking vasopressor medications were also at higher risk of kidney injuries.

Daniel Batlle, MD, the Earle, del Greco, Levin Professor of Nephrology/Hypertension at Northwestern University Feinberg School of Medicine in Chicago, said the study may be the best data available to date on the incidence of AKI in COVID-19 patients.

“The key thing about this paper is the temporal relationship, how quickly you see AKI when the patient goes to the intensive care unit (ICU) for intubation and the use of the respirator,” said Batlle, who was not involved in the study.

Kidney injuries are very common in ICU patients, but in COVID-19 patients they seem to be happening faster, Batlle said. In an observation that may boost understanding of potential mechanisms, Ng noted that the kidney damage appears to be caused by tubular injuries as a result of a loss of blood flow. Batlle and colleagues recently described what appears to be a multifactorial mechanism of AKI in patients with COVID-19 (2).

“It looks like this type of AKI is not the bread-and-butter AKI we see all the time,” Batlle said. In particular, he highlighted the high rate of blood clot formation and the need to give anticlotting agents to patients who require renal replacement.

The study also suggests a much higher incidence of AKI in hospitalized COVID-19 patients than previous studies, which have found rates as low as 5% in China (3) and 19% in Seattle (4), Ng said. A likely reason for the higher rate of kidney injury was that the patients included in this study had more comorbidities and were more likely to need mechanical ventilation than in other studies, Ng said.

The researchers also found that 14.3% of these patients required renal replacement therapy.

They expected a higher rate of AKI than previous studies based on what they were seeing in New York, said study co-author Kenar Jhaveri, MD, associate chief of the division of kidney diseases and hypertension at the Zucker School of Medicine at Hofstra University Northwell Health. “We expected the incidence to be at least above 20%,” he said. “What was surprising to us was that almost 15% of those with AKI ended up needing dialysis, or 5% [of all COVID-19 inpatients] needed dialysis. That was a little bit shocking.”

Like many health systems in New York and other hard-hit areas of the country, Northwell experienced a surge in demand for dialysis (5). The system had begun planning about a month before the surge and purchased more dialysis equipment and dialysis fluid. “We were on edge,” as patients started arriving, Jhaveri said. By moving supplies among the system’s 23 hospitals as needed they were able to keep up. But keeping up adequate staffing levels of nurses trained in dialysis was difficult, especially when some nurses became sick.

“We really had to make sure we had enough nursing staff and physician staff to take care of these patients,” Jhaveri said. “That was the biggest challenge.”

Jhaveri said he hoped the data would help hospitals prepare for potential future surges of coronavirus patients.

“If they know these numbers to get a better sense, okay, so if 35% get injuries, maybe we should add additional kidney doctors in the hospital instead of being in the office so that there’s enough manpower, so people don’t get burned out,” he said. “That’s where this is going to be very useful, in planning.”

Ng and Jhaveri plan to do further analyses of the patient data after 60 days, which may provide more insights about recovery rates from coronavirus-associated kidney injuries. Such longer-term data will be important to see how the condition evolves and how many patients recover, Batlle said.

The study was funded by the Feinstein Institutes for Medical Research at Northwell Health.