On the Basis of Race: The Utility of a Race Factor in Estimating Glomerular Filtration

Retaining Race in Chronic Kidney Disease Diagnosis and Treatment

The best overall measure of kidney function is glomerular filtration rate (GFR) as commonly estimated from serum creatinine concentrations (eGFRcr) using formulas that correct for the higher average creatinine concentrations in Blacks. After two decades of use, these formulas have come under scrutiny for estimating GFR differently in Blacks and non-Blacks. Discussions of whether to include race (Black vs. non-Black) in the calculation of eGFRcr fail to acknowledge that the original race-based eGFRcr provided the same CKD treatment recommendations for Blacks and non-Blacks based on directly (exogenously) measured GFR. Nevertheless, the National Kidney Foundation and the American Society of Nephrology Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease removed race in CKD treatment guidelines and pushed for the immediate adoption of a race-free eGFRcr formula by physicians and clinical laboratories. This formula is projected to negate CKD in 5.51 million White and other non-Black adults and reclassify CKD to less severe stages in another 4.59 million non-Blacks, in order to expand treatment eligibility to 434,000 Blacks not previously diagnosed and to 584,000 Blacks previously diagnosed with less severe CKD. This review examines: 1) the validity of the arguments for removing the original race correction, and 2) the performance of the proposed replacement formula. Excluding race in the derivation of eGFRcr changed the statistical bias from +3.7 to -3.6 ml/min/1.73m2 in Blacks and from +0.5 to +3.9 in non-Blacks, i.e., promoting CKD diagnosis in Blacks at the cost of restricting diagnosis in non-Blacks. By doing so, the revised eGFRcr greatly exaggerates the purported racial disparity in CKD burden. Claims that the revised formulas identify heretofore undiagnosed CKD in Blacks are not supported when studies that used kidney failure replacement therapy and mortality are interpreted as proxies for baseline CKD. Alternatively, a race-stratified eGFRcr (i.e., separate equations for Blacks and non-Blacks) would provide the least biased eGFRcr for both Blacks and non-Blacks and the best medical treatment for all patients.

Meropenem PK/PD Variability and Renal Function: "We Go Together"

BACKGROUND

Meropenem is a carbapenem antibiotic widely employed for serious bacterial infections. Therapeutic drug monitoring (TDM) is a strategy to optimize dosing, especially in critically ill patients. This study aims to show how TDM influences the management of meropenem in a real-life setting, not limited to intensive care units.

METHODS

From December 2021 to February 2022, we retrospectively analyzed 195 meropenem serum concentrations (Css). We characterized patients according to meropenem exposure, focusing on the renal function impact.

RESULTS

A total of 36% (n = 51) of the overall observed patients (n = 144) were in the therapeutic range (8-16 mg/L), whereas 64% (n = 93) required a meropenem dose modification (37 patients (26%) underexposed; 53 (38%) overexposed). We found a strong relationship between renal function and meropenem concentrations (correlation coefficient = -0.7; p-value < 0.001). We observed different dose-normalized meropenem exposure (Css/D) among renal-impaired (severe and moderate), normal, and hyperfiltrating patients, with a median (interquartile range) of 13.1 (10.9-20.2), 7.9 (6.1-9.5), 3.8 (2.6-6.0), and 2.4 (1.6-2.7), respectively (p-value < 0.001).

CONCLUSIONS

Meropenem TDM in clinical practice allows modification of dosing in patients inadequately exposed to meropenem to maximize antibiotic efficacy and minimize the risk of antibiotic resistance, especially in renal alterations despite standard dose adaptations.

Ethnic determinants of skeletal health in female patients with fragility fracture in a culturally diverse population

Background

Low bone density leads to fragility fracture, with significant impact on morbidity and mortality. While ethnic differences in bone density have been observed in healthy subjects, this has not yet been explored in fragility fracture patients.

Aims

To assess if ethnicity is associated with bone mineral density and serum markers of bone health in female patients who experience fragility fractures.

Methods

219 female patients presenting with at least one fragility fracture at a major tertiary hospital in Western Sydney Australia were studied. Western Sydney is a region with great cultural diversity, comprising people from over 170 ethnicities. Within this cohort, the three largest broad ethnic groups were Caucasians (62.1 %), Asians (22.8 %), and Middle Eastern patients (15.1 %). Location and nature of the presenting fracture and other relevant past medical history were obtained. Bone mineral density, measured by dual-energy X-ray absorptiometry, and bone-related serum markers were compared between ethnicities. Covariates (age, height, weight, diabetes, smoking, and at-risk drinking) were adjusted in multiple linear regression model.

Results

Although Asian ethnicity was associated with lower bone mineral density at the lumbar spine in fragility fracture patients, this association was no longer significant after adjustment for weight. Ethnicity (Asian or Middle Eastern) was not a determinant of bone mineral density at any other skeletal site. Caucasians had lower estimated glomerular filtration rate compared to Asian and Middle Eastern subjects. Serum parathyroid hormone concentrations were significantly lower in Asians compared to other ethnicities.

Conclusion

Asian ethnicity and Middle Eastern ethnicity were not major determinants of bone mineral density at the lumbar spine, femoral neck, or total hip.

Evaluating the Impact and Rationale of Race-Specific Estimations of Kidney Function: Estimations from U.S. NHANES, 2015-2018

BACKGROUND

Standard equations for estimating glomerular filtration rate (eGFR) employ race multipliers, systematically inflating eGFR for Black patients. Such inflation is clinically significant because eGFR thresholds of 60, 30, and 20 ml/min/1.73m2 guide kidney disease management. Racialized adjustment of eGFR in Black Americans may thereby affect their clinical care. In this study, we analyze and extrapolate national data to assess potential impacts of the eGFR race adjustment on qualification for kidney disease diagnosis, nephrologist referral, and transplantation listing.

METHODS

Using population-representative cross-sectional data from the United States National Health and Nutrition Examination Survey (NHANES) from 2015-2018, eGFR values for Black Americans were calculated using the Modification of Diet in Renal Disease (MDRD) equation with and without the 1.21 race-specific coefficient using cohort data on age, sex, race, and serum creatinine.

FINDINGS

Without the MDRD eGFR race adjustment, 3.3 million (10.4%) more Black Americans would reach a diagnostic threshold for Stage 3 Chronic Kidney Disease, 300,000 (0.7%) more would qualify for beneficial nephrologist referral, and 31,000 (0.1%) more would become eligible for transplant evaluation and waitlist inclusion.

INTERPRETATION

These findings suggest eGFR race coefficients may contribute to racial differences in the management of kidney. We provide recommendations for addressing this issue at institutional and individual levels.

FUNDING

No external funding was received for this study.

Use of Racial and Ethnic Categories in Medical Testing and Diagnosis: Primum Non Nocere

BACKGROUND

Use of race and ethnicity is common in medical tests and procedures, even though these categories are defined by sociological, historical, and political processes, and vary considerably in their definitions over time and place. Because all societies organize themselves around these constructs in some way, they are undeniable facets of the human experience, with myriad health consequences. In the biomedical literature, they are also commonly interpreted as representing biological heterogeneity that is relevant for health and disease.

CONTENT

We review the use of race and ethnicity in medical practice, especially in the USA, and provide 2 specific examples to represent a large number of similar instances. We then critique these uses along a number of different dimensions, including limitations in measurement, within- versus between-group variance, and implications for informativeness of risk markers for individuals, generalization from arbitrary or nonrepresentative samples, perpetuation of myths and stereotypes, instability in time and place, crowding out of more relevant risk markers, stigmatization, and the tainting of medicine with the history of oppression. We conclude with recommendations to improve practice that are technical, ethical, and pragmatic.

SUMMARY

Medicine has evolved from a mystical healing art to a mature science of human health through a rigorous process of quantification, experimentation, and evaluation. Folkloric traditions, such as race- and ethnic-specific medicine will fade from use as we become increasingly critical of outdated and irrational clinical practices and replace these with personalized, evidenced-based tests, algorithms, and procedures that privilege patients' individual humanity over obsolete and misleading labels.