Diagnosing Disparities: Racial Bias in Medical Testing and Devices
Healthcare is built on the principle of delivering safe, effective, and equitable care. Yet many diagnostic tools and tests still reflect systemic racial biases embedded in their design or use. From miscalculations in kidney function to inaccuracies in oxygen monitoring, several medical devices and investigations, originally based on homogenous populations, are failing to serve all patient groups equally. This essay explores how these disparities compromise care and why change is urgently needed.
Disclaimer: This section was compiled by a medical student using a range of academic and patient sources. It is not intended as clinical guidance. Feedback on outdated, inaccurate, or unclear content is warmly welcomed.
Kidney Function: eGFR and the Fallacy of Race Adjustment
The estimated glomerular filtration rate (eGFR) is a common measure of kidney function. It calculates how well the kidneys filter waste using variables like age, sex, and serum creatinine. Historically, many calculators also included race as a factor—based on the assumption that Black individuals have inherently higher serum creatinine levels.
This race-based adjustment has since been challenged. Studies show that it can falsely suggest better kidney function in Black patients, delaying urgent treatment and leading to inappropriate medication dosing. As Inserro and others highlight, using race in clinical algorithms risks reinforcing biases rather than reflecting biological truths. [1][2][3]
Lung Function: A Flawed 'Normal'
Pulmonary function tests, like spirometry, also incorporate race-based correction factors. Because Black patients tend to have lower average lung volumes, equations “normalize” these results—potentially underestimating the severity of respiratory disease.
Given the higher incidence of respiratory illnesses in Black communities, this misclassification can prevent timely treatment, limit transplant eligibility, and perpetuate unequal outcomes. Recognising and removing these flawed assumptions is essential to avoid disparities in respiratory care. [4]
VBAC Predictions and Racial Inequity
Vaginal birth after Caesarean (VBAC) calculators are used to assess whether a person is likely to safely deliver vaginally following a prior C-section. The widely used 2007 Maternal-Fetal Medicine Units (MFMU) calculator included race and ethnicity, predicting lower VBAC success rates for Black and Hispanic patients.
These biased predictions contributed to differences in care planning, with fewer opportunities for trial of labour among minority patients. Updated tools from 2021 have removed race as a variable, showing that doing so improves accuracy and helps address racial inequities in obstetric outcomes—especially crucial given the higher maternal mortality rates among Black women. [5]
Pulse Oximetry: Hidden Hypoxia in Black Patients
Pulse oximeters are non-invasive devices that estimate blood oxygen levels, essential in monitoring conditions like COVID-19. Yet, recent research has shown that these devices overestimate oxygen saturation in patients with darker skin tones, particularly in Black patients.
During the COVID-19 pandemic, these inaccuracies had dire consequences. Hypoxic Black patients were less likely to be hospitalised or receive oxygen therapy due to falsely reassuring oximeter readings. Studies by Valbuena et al. and Sudat et al. demonstrate how this disparity contributes to poorer outcomes in acute care settings. [6][7][8]
Forehead Thermometers: Temperature Bias and Missed Diagnoses
Temperature is a core component of patient assessment, guiding diagnosis and escalation of care. However, a study involving over 4,000 patients found that forehead thermometers consistently underestimated temperatures in Black patients compared to oral readings.
While 10.8% of White patients were detected as febrile by forehead thermometers, only 10.1% of Black patients were—even though oral thermometers revealed a fever in 13.2% of Black patients. This discrepancy could lead to under-diagnosis, delayed treatment, and poorer outcomes. [9]
Body Mass Index (BMI): A Misleading Metric
BMI, developed in the 1830s by Belgian statistician Adolphe Quetelet, remains a widespread tool for assessing body composition. However, it was derived from a narrow population of white European men and ignores key factors like muscle mass, ethnicity, and lifestyle.
For many populations, including Black and South Asian individuals, BMI is a poor predictor of health risk. It can pathologise healthy bodies or miss underlying conditions. In contrast, methods such as bioimpedance offer a more inclusive, individualised approach to assessing body fat and health. [10]
The examples above highlight an uncomfortable truth: many diagnostic tools in medicine were not designed with racial equity in mind. From kidney tests to thermometers, devices can mislead clinicians and undermine the care of patients from racially minoritised groups.
The solution lies not just in updating algorithms but in transforming how we think about medicine—moving away from race as a biological proxy and toward more accurate, inclusive, and person-centred care. By re-evaluating the tools we trust most, we can begin to close the gap in outcomes and create a healthcare system that truly works for all.
