Impaired kidney Function Linked To Worse Covid-19 Outcomes

Patients with renal impairment who become critically ill with COVID-19 fare worse than those with intact renal function, new findings show.

Mortality was more than twice as high for patients with acute kidney injury (AKI) or chronic kidney disease (CKD) compared with those with no renal impairment, and kidney-transplant patients' in-hospital mortality rate was 86%, Dr. Sanooj Soni of Imperial College London and colleagues found.

"Important differences exist between stages of acute and CKD in how they affect mortality in patients with COVID-19, and patients with renal transplantation are an extremely vulnerable group," they write in Anaesthesia. "Attention needs to be paid to patients with COVID-19 with any form of renal impairment and every effort made to prevent progression of renal injury in order to reduce mortality."

AKI incidence is far higher in COVID-19 patients who die from the infection, at 53% versus 1% for survivors, Dr. Soni and his team note. To investigate outcomes in patients with renal impairment before contracting the infection, they looked at 372 patients admitted to four regional intensive-care units (ICUs) in the U.K., 58% of whom presented with renal impairment.

Half of the patients with renal impairment died in the hospital, versus 21% of those with preserved renal function (P<0.001). Six of seven patients with kidney transplants died in the hospital, for a mortality rate of 86%.

COVID-19 survivors were also significantly less likely to have needed renal replacement therapy than non-survivors (24% vs. 46%).

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Based on Kidney Disease: Improving Global Outcomes classification, the mortality rate was 21% for patients with stage 0 and 49% for stage 1-3 (P<0.001).

One in five patients who required renal replacement while in the ICU continued to require it after hospital discharge.

The mechanisms behind kidney injury with COVID-19, and the worse outcomes in patients with renal impairment, are not clear, although inflammation is likely involved, Dr. Soni told Reuters Health by phone.

"We think there may well be some organ crosstalk" with the lungs, he added. It's also not clear why mortality was so high in transplant patients, he said, although it could be related to immunosuppressant therapy.

"What we can do as clinicians is to be alert to this," Dr. Soni said. "We can be careful in terms of managing how much fluid patients need, and keeping an eye on that."

—Anne Harding

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