In the era of changing ideas and a greater understanding of the disparities seen in healthcare, the conversation surrounding racial biases in medical investigations is necessary and relevant. Within this article, I will be defining some essential medical investigations, their role and the impact they have on racial inequalities in clinical practice (Vyas, D.A., Eisenstein, L. and Jones, D.R. 2020). The points mentioned in this piece have all been supported by an array of reputable studies, meta-analyses and reviews which have delved into the subject and uncovered one of the silent determinants of discrepancies in healthcare both domestically and internationally.
Pulse Oximetry
Pulse oximetry is a simple yet essential medical investigation used by practitioners around the globe. It consists of clipping a small device, called a pulse oximeter, to a patient’s fingertip; measuring the oxygen saturation of the patient’s blood through the use of wavelengths to detect the amount of oxygen binding to red blood cells (Torp, Modi and Simon, 2022). While this quick and simple examination has proven invaluable in determining oxygen levels, its accuracy falls compared to the measurement found in arterial blood gas tests. In a study carried out by Valbuena, V et al, it was found that the difference in accuracy between ABG and pulse oximetry meant that severely oxygen-starved (hypoxic- SaO2>88%) patients had been missed in pulse oximetry but shown in ABG readings. This phenomenon seems to occur more prominently in Black patients compared to their White counterparts. This would increase the likelihood of mortality and increase the chances of end-organ failure in patients with severe hypoxia (Valbuena, V et al., 2022). Therefore, the racial bias seen in the reduced accuracy of the oximeter paired with the disparity in measurements between ABG and pulse oximetry has led to a greater level of accurate and effective treatment for White patients in acute settings compared to Black patients.
Looking into a more recent case, Sudat, S et al, conducted a study during one of the peaks of the COVID-19 epidemic (July 2020- Feb 2021). This would focus on the systematic overestimation of blood oxygenation in NHB (non-Hispanic Black patients- one of the two categories measured in this study). Meaning, this 1% overestimation of blood oxygen would reduce the rate of admission, pharmacological treatment and oxygen therapy for COVID-19 patients from NHB backgrounds (Sudat, S et al., 2022). Thus exacerbating the racial disparities further in medical investigations and its impact on the outcome of treatment for specific racial groups.
eGFR
Whilst looking at commonly used medical investigations, the eGFR (estimated glomerular filtration rates) calculations stand as one of the most prominent in measuring kidney function and systemic maladies. However, based on studies conducted in the past three years, this investigation type has proven inaccurate and biased in the face of comparisons between Black and White patients. Current eGFR calculations use a person’s age, sex, and serum creatinine levels. Serum creatinine is a waste product from metabolism in the muscles, which is filtered by the kidneys (National Institutes of Health, 2021). These variables have now been noted to be biased in nature and unreliable as a form of investigation. Black Americans have been found to contain higher levels of serum creatinine regardless of kidney function, thus distorting the eGFR calculations to present with a lower level of kidney function than what is accurate (Williams, W.W., Hogan, J.W. and Ingelfinger, J.R, 2021).
Following this, an article by Inserro, A, presented the idea that using race as a determinant of risk and kidney function was harmful as it already embedded biases within the medical investigation without conducting clinical tests (Inserro, A., 2020). This meant that physicians were assigning the label of higher kidney function to Black patients, resulting in assumed treatment pathways alongside reduced severe care scenarios being enacted when needed and inaccurate pharmacological interventions being prescribed. Thus widening the discrepancy in the standard of care and medical management between Black and White patients.
The Future of Medical Investigations (Pulse Oximetry and eGFR)
In regards to what the future holds for medical investigations widely utilised like eGFR and pulse oximetry, the cited papers and studies highlight the need for further evaluation and reflection on the usability of said assessments and their impact on the clinical outcomes for patients of all racial backgrounds.
Looking at Valbuena, V et al and Sudat, S et al studies, the common denominator that can be extracted is the call for further research into the cause of these racial disparities within this commonly used medical assessment. As well as a push within the research and policy fields to revisit current policy and standards of devices used. Supporting this, Valbuena, V et al suggest that the National Health Service in the UK should only invest in devices that display no racial bias or inaccuracy in order to bridge the divide that has been created by the results found in these papers and potentially improve patient care and experience for non-White patients in future acute settings.
Strengthening this idea on evaluation and change; Williams, W et al, suggested adopting a revised version of the eGFR calculation (originally coined by Inker et al) which did not take race into consideration but included the measurement of serum cystatin C concentration (another protein filtered by the glomerulus) in the equation. The results found that using this revised equation yielded lower predictive bias and a greater agreement with measured GFR across race groups than GFR estimation based on creatinine alone. Thus highlighting the alterations that need to be made in order to reduce the bias witnessed within these medical investigations and therefore, influence the level of racial disparities seen in diagnosis, measurements and subsequently treatments.
References:
Vyas, D.A., Eisenstein, L. and Jones, D.R. (2020). Hidden in Plain Sight — Reconsidering the Use of Race Correction in Clinical Algorithms. [online] 383(9), pp.874–882. Doi: https://doi.org/10.1056/nejmms2004740.
Torp, K.D., Modi, P. and Simon, L.V. (2022). Pulse Oximetry. [online] Nih.gov. Available at: https://www.ncbi.nlm.nih.gov/books/NBK470348/
Valeria S.M. Valbuena, Seelye, S., Sjoding, M.W., Valley, T.S., Smits, H.H., Gay, S.L., Claar, D., Prescott, H.C. and Iwashyna, T.J. (2022). Racial bias and reproducibility in pulse oximetry among medical and surgical inpatients in general care in the Veterans Health Administration 2013-19: multicenter, retrospective cohort study. [online] pp.e069775–e069775. Doi: https://doi.org/10.1136/bmj-2021-069775.
Sudat, S., Wesson, P., Rhoads, K.F., Brown, S., Noha Aboelata, Pressman, A.R., Mani, A. and Kristen M.J. Azar (2022). Racial Disparities in Pulse Oximeter Device Inaccuracy and Estimated Clinical Impact on COVID-19 Treatment Course. [online] doi: https://doi.org/10.1093/aje/kwac164.
National Institutes of Health (NIH). (2021). NIH-supported study suggests alternative to race-based kidney function calculations. [online] Available at: https://www.nih.gov/news-events/news-releases/nih-supported-study-suggests-alternative-race-based-kidney-function-calculations
Inserro, A. (2020). Flawed Racial Assumptions in eGFR Have Care Implications in CKD. [online] AJMC. Available at: https://www.ajmc.com/view/flawed-racial-assumptions-in-egfr-have-care-implications
Williams, W.W., Hogan, J.W. and Ingelfinger, J.R. (2021). Time to Eliminate Health Care Disparities in the Estimation of Kidney Function. [online] 385(19), pp.1804–1806. Doi: https://doi.org/10.1056/nejme2114918.
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