CHICAGO, May 14 — Over a third of patients treated for Covid-19 in a large New York medical system developed acute kidney injury, and nearly 15 per cent required dialysis, US researchers reported today.

The study was conducted by a team at Northwell Health, the largest health provider in New York state.

"We found in the first 5,449 patients admitted, 36.6 per cent developed acute kidney injury,” said study co-author Dr Kenar Jhaveri, associated chief of nephrology at Hofstra/Northwell in Great Neck, New York, whose findings were published in the journal Kidney International.

Acute kidney injury occurs when the kidneys fail and become unable to filter out waste.

Of those patients with kidney failure, 14.3 per cent required dialysis, Jhaveri said in a phone interview.

The study is the largest to date 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 caused by the novel coronavirus that has infected more than 4.3 million people and killed over 295,000 globally.

Several groups have noted increased rates of kidney failure among patients with Covid-19. Jhaveri and colleagues set out to quantify it by combing through medical records of 5,449 Covid-19 patients hospitalised between March 1 and April 5.

They found that kidney failure occurred early on, with 37.3 per cent of patients arriving at the hospital with failing kidneys, or developing the condition within the first 24 hours of being admitted.

In many cases, the kidney failure occurred around the time severely ill patients needed to be placed on a ventilator, Jhaveri said.

Among the more than 1,000 patients who needed to be placed on a ventilator, about 90 per cent developed acute kidney failure. That compared with 21.7 per cent of the 925 patients who developed the condition but did not need mechanical breathing assistance.

Very ill patients often develop kidney failure as their conditions becomes more and more severe, Jhaveri said.

"It's not specific to Covid-19. It's more related to how sick you are,” he said.

Nevertheless, knowing the proportion of patients at risk for this condition could help hospitals as they plan equipment and staffing needed for future coronavirus surges, he said. — Reuters