Patients who recover from COVID-19 often face long-term health consequences. One of the most concerning is the damaging effects on kidney function, which might affect hundreds of thousands of survivors.

"Long COVID" often is seen to involve pulmonary effects, but extrapulmonary organ systems also can be involved, according to a recent study.

The report in the Journal of the American Society of Nephrology noted that "beyond the acute phase of illness, 30-day survivors of COVID-19 had higher risks of AKI [acute kidney injury], eGFR [estimated glomerular filtration rate] decline, ESKD [end-stage kidney disease], major adverse kidney events (MAKE), as well as greater longitudinal decline in eGFR." Researchers from the Department of Veterans Affairs' Saint Louis Health Care System Clinical Epidemiology Center and Washington University School of Medicine pointed out that the risks of kidney outcomes increased in line with the severity of the acute infection—whether the patient was nonhospitalized, hospitalized, or admitted to intensive care.

"Our findings emphasize the critical importance of paying attention to kidney function and disease in caring for patients who have had COVID-19," said senior author Ziyad Al-Aly, MD. "If kidney care isn't an integral part of COVID-19 post-acute care strategy, then we will miss opportunities to help potentially hundreds of thousands of people who have no idea that their kidney function has declined due to this virus. This is in addition to the millions of Americans who suffer from kidney disease not caused by COVID-19."Based on the research, Dr. Al-Aly suggested that more than a half-millionpatients who recovered from COVID-19 might have kidney injury or disease.

A cohort of 1.7 million veterans identified from March 1, 2020, to March 15, 2021, was used in the study. Patients included 89,216 30-day COVID-19 survivors and about 1.6 million noninfected controls. The team examined risks of AKI, eGFR decline, end-stage kidney disease, and MAKE, which is defined as eGFR decline >50%, ESKD, or all-cause mortality.

Results indicated that even following acute illness, 30-day survivors of COVID-19 exhibited a higher risk of AKI (adjusted hazard ratio [aHR] = 1.94 [95% CI: 1.86,2.04]), eGFR decline >30% (1.25 [1.14,1.37]), eGFR decline >40% (1.44 [1.37,1.51]), eGFR decline >50% (1.62 [1.51,1.74]), ESKD (2.96 [2.49-3.51]), and MAKE (1.66 [1.58,1.74]).

"There was a graded increase in risks of post-acute kidney outcomes according to the severity of the acute infection (whether patients were non-hospitalized, hospitalized, or admitted to intensive care," the researchers explained.

Compared with noninfected controls, 30-day COVID-19 survivors exhibited excess eGFR decline of -3.26 (-3.58, -2.94), -5.20 (-6.24, -4.16), and -7.69 (-8.27, -7.12) mL/min/1.73 m2/year in nonhospitalized patients, hospitalized patients, and those admitted to intensive care during the acute phase of COVID-19 infection.

Because they were older veterans, most COVID-19 patients in the study were male and in their late 60s. However, the researchers also analyzed data that included 151,289 women—including 8,817 with COVID-19—as well as adults of all ages. It was found that among COVID-19 patients, 12,376 (13.9%) required hospitalization, including 4,146 (4.6%) who were admitted to intensive-care units.

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