Study Assesses the Utility of Renal Genetic Testing in Black Patients

Chronic kidney diseases are common, with a global prevalence rate of approximately 12% to 15%. Black patients are almost four times more likely to develop kidney failure compared to white patients. In the United States, Black individuals account for approximately 35% of kidney failure patients even though they only make up only about 13% of the population with chronic kidney disease.

It has been hypothesized that genetic risk factors may play a role in the evident disparities in kidney disease outcomes. Although genetic testing is becoming increasingly accessible to patients with kidney diseases, little is known about racial disparities in renal genetics evaluations.

Understanding the impact of renal genetic testing on patient management

A study led by a team of Cleveland Clinic investigators aimed to assess the utility of renal genetics testing in a cohort of patients with kidney disease managed at Cleveland Clinic’s Renal Genetics Clinic. Study results were published in the July 2023 issue of Kidney International Reports.

“Our previous study has shown the importance of integrating genetic testing to the work up of kidney patients, and our data has clearly shown the great benefit for patients in terms of the diagnosis and management,” says Cleveland Clinic nephrologist and medical geneticist Xiangling Wang, MD, PhD, founding director of Renal Genetics Program and corresponding author of the study. “Genetic testing is increasingly accessible to patients with kidney diseases while racial disparities in renal genetics evaluations have not been investigated.”

The study included 48 Black patients and 232 white patients seen in Cleveland Clinic’s Renal Genetics Clinic between January 2019 and March 2022. In this cohort, 56.3% of Black patients and 32.8% of white patients were males, respectively.

“The key features that we assessed were clinical and laboratory characteristics including kidney function at the index visit to the Renal Genetics Clinic, genetic testing modalities and diagnostic implications of Black and white patients with kidney disease. Dr. Wang says, “This study, for the first time, examined racial disparities in renal genetics evaluation and uncovered several significant findings.”

Patient records were reviewed independently by two researchers. DNA samples were retrieved from blood or buccal swabs. Genetic testing was performed in certified laboratories, and the results were categorized into five different groups based on the identified variants and genes.

Genetic testing benefits Black and white patients equally while barriers exist

Review of patient records revealed Black patients were more likely to have end-stage kidney disease (ESKD) at the time of referral compared with white patients (23% vs. 7.3%), more likely to be covered by Medicaid (46% vs. 15%, P < 0.001), and less likely to be covered by private insurance (35% vs. 66%, P < 0.001). Moreover, Black patients were more likely to “no show” to scheduled appointment(s) or not submit specimens for genetic testing compared with white patients (24.1% vs. 6.7%). “This indicates that substantial barriers in access to genetic testing exists among Black patients with kidney disease,” Dr. Wang adds.

In terms of the diagnostic yield of genetic testing, there were no statistical differences between Black and white individuals, with 37% of Black patients and 42% of white patients having positive results. After receiving a positive finding, 69% of Black individuals received a new diagnosis or had a change in their diagnosis. No differences in diagnostic yield were noted between Black and white patients.

Further, “about 44% of [Black] patients received a significant change in their management, which did not differ when compared to white patients,” Dr. Wang says, noting that Black patients with kidney disease equally benefit from genetics evaluation compared with white patients, and steps must be taken to ensure equitable and early access for all patients.

Removing the barriers

She believes that the key to removing the existing barriers to renal genetic testing for Black patients lies in additional studies to explore the barriers from both patients’ and physicians’ perspectives and tailored education and counseling on genetic testing for Black patients to empower them in making informed decisions.

“We are conducting further studies to better understand and address these barriers, aiming to enhance the tailored education and counseling provided to Black patients with kidney disease. Comprehensive efforts are needed to develop policies addressing the social and ethical aspects of renal genetics,” she concludes.