Illustration of two kidneys

Adoption of a highly recommended race-neutral measurement of kidney function would result in new kidney disease classifications for 5.5 million patients out of 39,000, a new study has found.

In 2021, leading kidney care organizations urged clinicians to transition away from using a race-based equation for estimating stages of chronic kidney disease, which help determine treatment levels. The current standard measure uses age, sex, race (Black vs. non-Black) and creatinine level to estimate glomerular filtration rate (GFR) and disease stage. But this equation is outdated and risks kidney disease misdiagnosis for Black patients, who experience kidney failure at three times the rate of whites, according to the National Kidney Foundation and other patient advocates.

Investigators used patient data from the U.S. National Health and Nutrition Examination Survey to determine the effect of switching to the race-neutral equation. Their analysis showed that compared with disease staging with the older race-based equation, the new equation altered chronic kidney disease stage classifications for millions of these patients, mostly in the moderate stages of disease.

More black patients’ disease “severe” 

Among the 5.5 million patients whose CKD stages were reclassified using the new equation, 1 million were reclassified into a more severe stage and 4.5 million into a less severe stage. All persons reclassified into more severe stages (3.9%) self-reported as Black, while all persons reclassified into less severe stages (2.2%) self-reported that they were non-Black.

Kidney disease complications did not appear to be substantially altered in the current study, the researchers noted. This could be due to the use of a single laboratory for data collection, they said. The presence of CKD complications are used to validate staging that uses GFR thresholds, especially when patients are at more severe stages of disease. 

Overall however, the reclassification rate using the race-neutral equation was substantial, and could affect diagnosis and treatment for many patients, the authors concluded.

The study was published in JAMA Network Open.