Trying to better understand the impact of the coronavirus, researchers are taking a closer look at its effects on those who have been diagnosed with the virus.

In New York, a hospital study showed coronavirus is causing damage to patients’ organs, with the kidneys being particularly affected. Knowing the proportion of patients at risk for such damage could help hospitals as they plan for future coronavirus surges.

A team at Northwell Health, the largest health provider in New York state, found that over a third of the patients treated for COVID-19 developed acute kidney injury and nearly 15% required dialysis.

“We found in the first 5,449 patients admitted, 36.6% developed acute kidney injury,” study co-author Dr. Kenar Jhaveri, associated chief of nephrology at Hofstra/Northwell in Great Neck, New York, told Reuters.

The study is the largest so far to look at kidney injury in COVID-19 patients. It may be helpful, Jhaveri said, as other hospitals face new waves of patients with the disease, which has infected more than 4.3 million people and killed over 295,000.

Acute kidney injury (AKI) causes a rapid decline in kidney function, which can lead to long-term damage and even death. The condition causes a build-up of waste products in the blood and makes it difficult for the kidneys to keep the right balance of fluids.

Risk factors for developing the condition include age, diabetes, heart disease, and hypertension. Older males and black patients with COVID-19 were at high-risk for kidney failure, the study found.

The researchers analyzed electronic health records of 5,449 hospitalized coronavirus patients between March 1 and April 5, finding that 36.6% ( 1,993) of these patients developed AKI. By the study’s conclusion, 39% of AKI patients were still hospitalized.

“Working amidst the COVID-19 epicenter was an experience we will never forget. Nephrologists and the dialysis staff were on the front lines of this battle trying to help every patient we could,” Jhaveri said. “We hope to learn more about the COVID-19 related AKI in the coming weeks

Among the more than 1,000 patients who needed to be placed on a ventilator, about 90% developed acute kidney failure. Only 21.7% of the 925 patients who developed the condition did not need mechanical breathing assistance. Very ill patients often develop kidney failure, Jhaveri said.

The team is currently involved in several other studies on patients with COVID-19. They recently found that nearly all coronavirus patients had at least one underlying medical condition that put them at risk of contracting the killer bug.

The study was published in the journal Kidney International.