Elimination of race in eGFR equation does not affect links to dementia, stroke
Key takeaways:
- Newer eGFR calculations that do not consider race show a link between kidney function and dementia.
- Equations with and without race showed similar risks by eGFR level, but some individuals changed categories.
When eGFR was calculated using creatinine and cystatin C and without adjusting for race, adults with eGFR less than 60 mL/min/1.73 m2 had greater risk for dementia, but not for stroke, than those with normal eGFR, according to study data.
“Clinical laboratories commonly calculate a patient’s eGFR using only serum creatinine. A National Kidney Foundation-American Society of Nephrology task force recently recommended the adoption of eGFR measured with serum creatinine, without consideration of Black race, to be adopted by all laboratories in the United States. They also advocated for increased usage of cystatin C in calculations of eGFR as this measure is more accurate,” Samuel R. Moen, MPH, James S. Pankow, PhD, and Sanaz Sedaghat, PhD, all in the division of epidemiology and community health and the University of Minnesota School of Public Health in Minneapolis, told Healio. “Our research provides updated risk estimates of stroke and dementia using new measures of eGFR to modernize newly outdated findings that were determined using a problematic measure of eGFR.”
Using data from the Multi-Ethnic Study of Atherosclerosis on 6,814 adults (mean age, 62 years; 53% women; 39% were white; 27% were Black; 12% were Chinese American; 22% were Hispanic/Latino) collected between 2000 and 2002, Moen, Pankow, Sedaghat and colleagues analyzed associations of dementia and stroke with eGFR using an equation that included cystatin C and eliminated race. They then compared risks when eGFR was calculated with four different equations: two that included consideration of Black race and two that did not use race, and in each of those categories, one equation used creatinine alone and the other used creatinine and cystatin C.
During 14.2 years of follow-up, there were 574 incident cases of dementia (incidence rate of 6.08 per 1,000 person years) and 349 incident strokes (incidence rate of 3.7 per 1,000 person years).
After adjustments, adults with eGFR less than 60 mL/min/1.73 m2 had 73% greater risk for dementia than those with higher eGFR (HR = 1.73; 95% CI, 1.21-2.45). Dementia risk increased by 8% for each additional 15 mL/min/1.73 m2 lower eGFR (HR = 1.08; 95% CI, 1-1.18). Stroke risk was not significantly associated with eGFR, according to researchers.
Differences in associations of dementia and stroke with different eGFR equations were “minimal,” according to the researchers, but these were still larger than differences in HRs for Black and other races.
“Outdated measures of eGFR were determined to overestimate kidney function in Black individuals, leading to disparities in access to care,” the researchers told Healio. “In Black participants, reclassification [based on equations without race] was almost always from a better to worse kidney function category. By contrast, reclassification was always from a worse to better kidney function category in non-Black participants. The extent of reclassification in the new equations was greater in Black participants. ... Although the new calculations of eGFR have minimal impact on point estimates of kidney function, these changes are imperative for people who are at or above the cut point of a kidney disease diagnosis. Having a lower eGFR, especially in Black individuals, is important for access to treatment.”
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