A ‘Race-Free’ Approach to Diagnosing Kidney Disease

A scientific task force on Thursday called for jettisoning a common measure of kidney function that adjusts results by race, providing different assessments for Black patients than for others.

The adjustment may make Black patients seem less ill than they really are, according to many experts. Instead, doctors should rely on a race-neutral method for diagnosing and managing kidney disease, concluded a report from the National Kidney Foundation and the American Society of Nephrology.

The specific equation recommended was described in a study published Thursday in the New England Journal of Medicine.

If adopted, the new approach would affect hundreds of millions of kidney function tests performed yearly in hospitals and outpatient settings, both for acutely ill patients and as part of routine screening blood tests. By one estimate, one million Black Americans might be treated earlier for kidney disease if the diagnostic equation were not adjusted for race.

The task force report, published concurrently in the American Journal of Kidney Diseases and the Journal of the American Society of Nephrology, comes amid a national reckoning over racial health disparities spurred by the Covid-19 pandemic, which has taken a disproportionate toll on people of color and has highlighted the excessive burdens of chronic disease in those communities.

“The issue is a moral issue,” said Dr. Neil R. Powe, co-chair of the task force and chief of medicine at Zuckerberg San Francisco General Hospital and Trauma Center. “It is time to remove race from the equation.”

Black and Hispanic Americans have long suffered from high rates of conditions such as diabetes, high blood pressure and obesity, which can exacerbate a bout of Covid. These factors can also increase the risk of developing kidney disease.

The racial disparities in kidney disease are stark and well documented. Black Americans are more than three times as likely as white Americans to experience kidney failure and require dialysis or a kidney transplant.

Though Black Americans make up only 13 percent of the population, they represent 35 percent of Americans with kidney failure. More than 90,000 Americans are on a waiting list for a kidney; nearly one-third are Black, about as many as those who are white.

People of color and low-income Americans are less likely to receive good care when the warning signs first appear and chronic kidney disease could be prevented. They are more likely to progress to kidney failure and to require dialysis, and less likely to be cared for by a kidney specialist before getting to that stage, according to a report by the Centers for Medicare and Medicaid Services.

Black Americans also wait longer for an organ, and are less likely to have a kidney donated by a friend or relative, for a variety of complex reasons.

“This new recommendation will ensure that racial biases are not introduced to clinical care, so someone will no longer be judged based on their race and have their skin color dictate what kidney care they receive,” said Dr. Nwamaka Denise Eneanya, a nephrologist at the University of Pennsylvania and a member of the task force.

Her work suggests that current measures used to assess kidney function may underestimate the severity of illness in Black patients, delaying referrals to specialists and making them less likely to be placed on waiting lists for a kidney transplant.

“Black individuals are inadvertently harmed because they are seen as not sick enough,” Dr. Eneanya said.

Other task force members cautioned that the impact of the change on patient outcomes was uncertain, and called on researchers to follow up to evaluate its impact.

The use of medical decision-making tools that take race and ethnicity into account is not unique to kidney disease. Algorithms and calculators that doctors rely on to guide diagnosis and treatment for many conditions — from bone density and kidney stones, to cancer and pulmonary function tests — include race as a variable, as outlined in a paper published last year in the New England Journal of Medicine.

“Race is a social construct and not a biological one,” said Dr. Winfred Williams, associate chief of the renal division at Massachusetts General Hospital in Boston, who co-wrote an editorial on the new equations.

“It may be serving as a proxy for other risk factors including food insecurity, housing insecurity, socioeconomic deprivation, all of which can limit access to best health care practices.”

In recent months, several medical societies have taken steps to address the potential bias. In May, the American Academy of Pediatrics officially dropped a practice guideline that considered the race of a baby when evaluating the risk of a urinary tract infection.

The American College of Obstetricians and Gynecologists is currently updating an algorithm that has included race and ethnicity in a calculator used to assess the chances a pregnant woman will have a successful vaginal birth after a previous cesarean section.

The new report that reassessed the inclusion of race in the diagnosis of kidney diseases was issued Thursday, after a year of work and no small degree of controversy along the way, the authors said.

The kidneys filter toxins from the blood. The new report recommends using a new equation to estimate the filtration rate using a blood test that measures levels of creatinine, a waste product made by muscles that is kept in check when the kidneys are functioning properly.

A related study, also published Thursday in the New England Journal of Medicine and cited in the report, developed and evaluated new diagnostic methods that do not include race as a variable. The researchers concluded that the new creatinine equation could be adopted immediately.

But the most accurate, race-neutral way to measure kidney filtration rates would incorporate blood tests that measure the level of a different marker: a protein produced by cells called cystatin C, which is elevated when kidneys are not functioning well, researchers said.

Tests of cystatin C are more expensive and not as widely available, but experts called for making them more accessible and gradually increasing their use.