How Bias Persists

Racially biased findings have permeated clinical research, even in recent decades.

by Joy Howard

In 2020, Mass General Brigham removed race from the calculation of eGFR, a measure of kidney function.

The false notion that Black people are biologically different from white people is centuries old, and often propagated by medical doctors and historians in journals and other publications. Persistent racial disparities in well-being, healthcare, and access to care are rooted in this bias.

In 1787, Thomas Jefferson wrote extensively in “Notes on the State of Virginia” about innate differences between Black and white people. Without evidence, he opined that Black people “secrete less by the kidneys.” More than 200 years later, medical researchers continued to claim that Black people’s kidneys differed from those of non-Black people.

In 1999, researchers studying 1,628 people with chronic kidney disease (CKD)1 gathered a cohort comprising 80% white people and 12% Black people. The remaining 8% included individuals from other races, who were grouped with white people in the study.

Titled “A More Accurate Method to Estimate Glomerular Filtration Rate From Serum Creatinine: A New Prediction Equation,” the study consistently found higher levels of creatinine—normally a sign of lower kidney function—in the Black participants than in the non-Black people.

“We have 10 more race adjustments I’m trying to address across our system.” —Tom Sequist, MD, MPH

Knowing that creatinine is higher in individuals with higher muscle mass, but without measuring the study participants’ muscle mass, the researchers stated, “Previous studies have shown that on average, black persons have greater muscle mass than white persons.”

To justify this claim, they cited three small studies comparing Black and white bodies:

  • A 1977 study comparing “body elemental composition” in 47 “normal” Black people from ages 34 to 68 to findings of a study of 67 “normal” white people of a similar age range.2
  • A 1978 study comparing body measurements in 242 schoolchildren in Louisiana, 143 white children and 99 Black children. Authors of that study noted, “Race was determined visually.”3
  • A 1990 study comparing creatine levels in 30 Black and 30 white healthy hospital
    workers, matched for age, sex, and body weight.4

A follow-up study in 20095 was more racially diverse than the first and revised the recommended race inflation from 21% to 15.9%, but, again, only for Black people.

Importantly, neither the 1999 nor the 2009 study explained how participants’ race was determined, or whether they were aware of how they were racially profiled. In 2006, a follow-up paper by some of the same authors6 stated that in the 1999 study, “Ethnicity was assigned by study personnel, without explicit criteria, probably by examination of skin color.” However, in March 2021, that statement in the 2006 paper was changed without elaboration or explanation to say, “Ethnicity was self-identified by the participants.”


Though research has dispelled the myth of biologic differences between races, the Brigham is still rooting out race-based algorithms in healthcare.

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“The history of the use of race and ethnicity in patient research is problematic and challenging for us all to confront. But this very challenge highlights the need for much stricter scrutiny of patient race data in research methods than is being given across the peer-reviewed literature,” says Tom Sequist, MD, MPH, Brigham internist and chief patient experience and equity officer for Mass General Brigham. “Academic medicine must do and be better. We must be transparent about previous practices and break with our broken past if we’re going to achieve equity and inclusion, for our patients and practitioners.”


1 Levey AS, Bosch JP, Lewis JB, et al. “A more accurate method to estimate glomerular filtration rate from serum creatinine: A new prediction equation.” Modification of Diet in Renal Disease Study Group. Ann Intern Med. 1999;130(6):461–470.
2 Cohn SH, Abesemis C, Zanzi I, et al. “Body elemental composition: comparison between black and white adults.” Am J Physiol. 1977;232:E419-22.
3 Harsha DW, Frerichs RR, Berenson GS. “Densitometry and anthropometry of black and white children.” Hum Biol. 1978;50:261-80. 43.
4 Worrall JG, Phongsathorn V, Hooper RJ. “Racial variation in serum creatine kinase unrelated to lean body mass.” Br J Rheumatol. 1990;29:371-3.
5 Levey AS, Stevens LA, Schmid CH, et al. “A new equation to estimate glomerular filtration rate.” Ann Intern Med 2009;150(9):604-612.
6 Levey AS, Coresh J, Greene T, et al. “Chronic Kidney Disease Epidemiology Collaboration. Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate.” Ann Intern Med. 2006 Aug 15;145(4):247-54. doi: 10.7326/0003-4819- 145-4-200608150-00004. Erratum in: Ann Intern Med. 2008 Oct 7;149(7):519. Erratum in: Ann Intern Med. 2021 Apr;174(4):584. PMID: 16908915.