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The Discrepancies in Pulse Oximetry: Examining Racial Bias in Medical Devices

Oakland, California — A patient in his 60s, an African American man suffering from emphysema, presented with a pulse oximeter reading that indicated his blood oxygen saturation was comfortably above the critical 88% threshold, which marks a dangerous risk of organ failure. Despite this, his physician, Noha Aboelata, suspected that he was in worse condition than the device suggested and ordered a laboratory test, which confirmed her concerns and indicated the need for supplemental oxygen at home.

Months later, while reading an article in the New England Journal of Medicine, Aboelata learned that pulse oximeters were three times more likely to fail in detecting dangerously low blood oxygen levels in Black patients when compared to white patients. This revelation was particularly alarming given the context of high COVID-19 mortality rates among Black Americans and the healthcare system’s struggles to provide necessary resources like oxygen.

“I found myself wondering if I’d missed other patients,” Aboelata reflected, highlighting the frustration and anger felt among her colleagues. They had trusted the pulse oximeter, only to find it systematically unreliable for the communities they served.

In response to growing concerns, state attorneys general and U.S. senators urged the FDA to combat the racial biases inherent in pulse oximetry, which have hindered timely treatment and resulted in adverse health outcomes.

Aboelata’s clinic has initiated legal action against producers and retailers of oximeters, demanding either their removal from shelves or a clear indication of their limitations on the packaging. The accuracy of these devices is vital for many patients, especially for those reliant on home oxygen, as accurate readings are necessary for Medicare reimbursement.

Despite their shortcomings, pulse oximeters play an indispensable role in the management of various respiratory and cardiac conditions, as well as in the diagnosis of sleep apnea. The devices have largely supplanted more invasive arterial blood gas tests, which, while more accurate, carry risks if improperly conducted. The pulse oximeter market is projected to generate about $3 billion this year alone, with widespread use across hospitals, clinics, and home settings during the pandemic.

Walter Wilson, a San Jose businessman aged 70, provides a personal account of the potential consequences of oximeter inaccuracy. After contracting COVID-19, he relied on his home oximeter readings, which showed normal oxygen levels, delaying his visit to a physician. “I’m a dark-complected Black guy. I was very sick. Had the oximeter picked that up, I would have gotten to the hospital sooner,” he recalled, ultimately ending up back on dialysis after a previous period of good health. Wilson is now considering joining a class-action lawsuit against the manufacturers of these devices.

“They’ve known for years that people with darker skin get bad readings,” he stated, emphasizing the importance of relevant clinical testing.

After years of minimal response from regulatory bodies, the FDA issued a safety warning in 2021 regarding pulse oximeter accuracy, alongside promises for improved research and updated guidelines. Expectations for these guidelines include recommendations for manufacturers to include a broader demographic in testing, particularly individuals with darker skin—an acknowledgment of long-standing disparities.

However, the implementation of these guidelines may be met with significant industry resistance. Experts like Michael Lipnick of UCSF caution against simply requiring manufacturers to test their devices in lab-pristine conditions rather than real-world scenarios, where many patients experience low perfusion—a condition characterized by inadequate blood flow that can diminish the accuracy of readings.

Pigment levels in the skin, combined with low perfusion, can severely impair pulse oximetry performance. Philip Bickler, director of the Hypoxia Research Lab at UCSF, notes that disparities in healthcare access have compounded these issues, often leaving Black patients to seek treatment only in the most critical circumstances.

A History of Regulatory Inaction

Data suggests that while some recent studies sponsored by industry players indicate improvements in device accuracy across skin tones, a substantial body of research through the decades has highlighted these persistent inaccuracies. Back in 2005, Bickler and his colleagues documented failures in several leading oximeters to detect hypoxemia in patients with darker skin, particularly those in severe distress. They advocated for devices to include warnings about their limitations.

The FDA’s response has historically been insufficient. The agency facilitated the market entry of oximeters based on the premise of “substantial equivalence” to existing products. While initial guidelines in 2007 recommended testing with a significant number of dark-skinned subjects, the finalized policy in 2013 allowed for only a minimal representation, further perpetuating inequalities.

Testing often involves subjecting patients to controlled breathing environments while collecting simultaneous readings from both pulse oximeters and more accurate arterial blood gas samples. Bickler expressed skepticism toward manufacturers, suggesting their claims of accuracy should be treated with caution.

During the pandemic, a medical charity approached Bickler’s lab for assistance in donating oximeters to impoverished nations. Upon reviewing selected devices, Bickler noted deficiencies in quality, prompting the establishment of an independent rating page that evaluates pulse oximeters much like a consumer goods review platform. Their findings revealed a significant gap in quality assurance, with many marketed devices failing to meet industry standards.

As the FDA funded studies on the feasibility of real-world testing, Bickler noted the lab’s approach diverged from conventional methods by not artificially warming patients’ hands—a practice that ensures better circulation during device testing. The absence of this step reflects actual patient conditions, where perfusion issues are commonplace.

Despite a willingness from some manufacturers, such as Masimo, to comply with forthcoming guidance, the conversation about equitably addressing these disparities continues. The most accurate devices often carry a steep price tag of $6,000 or more, raising concerns about accessibility and equity in healthcare.

Moving Forward

The anticipated focus on diversity in testing will serve as a pivotal step toward ensuring pulse oximeters function appropriately across all demographic groups. However, the challenge remains in how to balance cost and accuracy. Aboelata noted that some manufacturers have begun issuing warnings about their devices following legal actions, but the day-to-day practices of clinicians remain limited in scope.

Legislative efforts, such as Connecticut’s law prohibiting insurers from denying services based solely on oximetry readings, aim to address the ramifications of these inaccuracies. However, experts like Theodore Iwashyna emphasize that simply adapting protocols around flawed devices misses the mark—the solution genuinely lies in developing more reliable tools for patient care.

This article was produced by KFF Health News, a national newsroom focused on health issues, and is part of KFF, an independent source for health policy research, journalism, and public education.

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