New FDA Recommendations Aim to Fix Pulse Oximeter Bias in Skin Tones

Decades-Old Problem of Pulse Oximetry Across Skin Tones Targeted by New Draft FDA Guidance

For decades, pulse oximeters, the common medical devices used to estimate blood oxygen levels, have been known to provide inaccurate readings, particularly for individuals with darker skin tones. This issue, which has serious implications for patient care, is finally receiving the attention it deserves, thanks to new draft recommendations issued by the U.S. Food and Drug Administration (FDA). These guidelines aim to ensure that pulse oximeters perform accurately across all skin tones, addressing longstanding disparities in how these devices work for people of different racial and ethnic backgrounds.

What is a Pulse Oximeter and How Does It Work?

Pulse oximeters are widely used to measure two critical health parameters: heart rate and oxygen saturation levels. Oxygen saturation refers to the percentage of red blood cells carrying oxygen, a key indicator of how well a person’s lungs are functioning. These devices work by emitting light through a person's finger or earlobe. The light passes through the tissue, and a sensor on the opposite side of the body detects the amount of light that is not absorbed by the blood and tissues. This measurement is then used to estimate the oxygen saturation level in the blood.

Why This Matters: The Inaccuracy of Pulse Oximeters for Darker Skin Tones

While pulse oximeters are convenient and non-invasive, their accuracy can be affected by skin pigmentation. The presence of melanin, the pigment responsible for darker skin tones, can interfere with how light is absorbed and reflected by the skin, leading to misleading readings. Research has shown that individuals with darker skin tones often receive falsely high oxygen saturation readings, which can delay the recognition of medical issues, such as hypoxia (low oxygen levels in the blood).

The problem is not a new one. As early as 1990, studies began to show that Black patients on ventilators received less accurate pulse oximeter readings than their white counterparts. In one notable study, 27% of Black patients had inaccurate oxygen readings compared to just 11% of white patients. Despite this, the issue largely remained under the radar until the COVID-19 pandemic.

The COVID-19 Pandemic Brings New Urgency

The urgency of addressing pulse oximeter inaccuracies came into sharper focus during the COVID-19 pandemic. A 2023 study published in JAMA Network Open found that, in a sample of over 24,000 hospitalized patients, pulse oximeters more frequently overestimated oxygen levels in patients from minority racial and ethnic groups. These false readings had potentially serious consequences, including delayed recognition of respiratory failure in Black patients compared to their white peers.

As Eric Gottlieb, a clinical fellow in medicine at Brigham and Women's Hospital, noted in 2022, “Pulse oximeters give us an estimate, but it’s more than just a number. We use that estimate to make clinical decisions, such as how much supplemental oxygen to give a patient.” The disparities in oxygen monitoring highlighted by these studies are contributing to racial disparities in medical treatment, particularly for conditions like COVID-19.

What Does the New FDA Draft Guidance Propose?

In response to the growing body of research, the FDA has issued a new set of draft guidelines aimed at improving pulse oximeter accuracy across different skin tones. Previously, pulse oximeter manufacturers were primarily testing their devices on a limited sample, often not including enough diversity to assess performance accurately across the full spectrum of skin tones. The FDA’s new draft guidance calls for manufacturers to ensure that clinical trials for pulse oximeters include participants from diverse racial and ethnic backgrounds.

Specifically, the draft recommends that manufacturers test their devices on at least 150 people, with a diverse mix of skin tones as defined by the Monk Skin Tone Scale, which categorizes skin pigmentation from light to dark. The guidance also emphasizes the need for both objective and subjective assessments of skin tone in these studies, ensuring that no group is underrepresented.

Will the FDA’s New Guidance Make a Difference?

Although the new FDA recommendations are a positive step, there’s no guarantee they will lead to significant change. The draft guidance is open for public comment for the next 60 days, and after that, it remains up to manufacturers to voluntarily adopt these recommendations. While some experts, like Michael Sjoding from the University of Michigan, are hopeful that manufacturers will see the value in demonstrating the accuracy of their devices across all skin tones, others, like Theodore J. Iwashyna, are more skeptical. Iwashyna, who co-authored studies on pulse oximeter accuracy disparities, argues that unless there are formal enforcement mechanisms to ensure compliance, the new guidelines may have limited impact.

Even if manufacturers do comply, the change could take time to translate into improved patient care. Nonetheless, there’s hope that the guidelines will eventually reduce disparities and improve the accuracy of pulse oximeters, particularly for patients of color, who have historically been disadvantaged by inaccurate readings.

The Road Ahead: Addressing Disparities in Medical Devices

This new FDA draft guidance shines a light on the long-overlooked issue of racial disparities in medical technology. It highlights the need for more inclusive research and the development of devices that account for the diversity of the populations they serve. While the draft guidance is an important first step, it’s clear that more action is needed to ensure that medical devices are equitable for everyone, regardless of skin tone.

The problem of pulse oximeter inaccuracy also brings broader attention to the need for better representation and inclusion in clinical studies and medical device development. By acknowledging and addressing these disparities, the FDA’s recommendations may help pave the way for more accurate, equitable healthcare for all patients.