A new battle is emerging in the fight for health equity, and it’s centered on the humble pulse oximeter. On November 1, 2023, 25 state attorneys general sent a letter to the Food and Drug Administration (FDA) demanding that the agency take urgent action to address pulse oximeter inaccuracies that continue to create health care risks for people of color. The letter comes exactly one year after a public meeting held by the Anesthesiology and Respiratory Therapy Devices Panel of the FDA’s Medical Devices Advisory Committee titled “Pulse Oximeter Accuracy and Limitations,” and nearly 21 months after the agency issued a safety communication about pulse oximeter inaccuracies when used on people with dark skin pigmentation (see our previous blog post on pulse oximeter performance here). Led by California Attorney General Rob Bonta, and co-signed by the attorneys general of Arizona, Colorado, Connecticut, Delaware, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, Nevada, New Jersey, New Mexico, New York, North Carolina, Ohio, Oregon, Pennsylvania, Rhode Island, Utah, Vermont, Washington, Wisconsin and the District of Columbia, the letter cites multiple documented failures of pulse oximeters in health care environments, including some new studies published since FDA’s public meeting in 2022.

Based on the growing evidence that the limitations of pulse oximeters are causing immediate risks to a large patient population, the state attorneys general request immediate action from FDA to warn health care professionals and patients of the limitations of current pulse oximeter technology. Specifically, the letter asks the agency to immediately prioritize the following actions:

1.     Require pulse oximeter labeling to include clear warnings about reduced accuracy based on skin tone.

2.     Require similar warnings for any medical technology that incorporates data from pulse oximeters, such as medical software used for diagnosis or treatment.

3.     Update FDA’s February 2021 safety communication on pulse oximeters to incorporate recent evidence on the limitations of such devices.

4.     Issue letters directly to health care professionals and institutions describing the risks associated with the reduced efficacy of pulse oximeters on patients with darker skin tones.

5.     Accelerate the review and public release of the Medical Devices Advisory Committee’s recommendations to address pulse oximeter limitations.

6.     Implement regulations requiring demographically diverse clinical trials for “previously approved medical devices like pulse oximeters.”

It is interesting to note that the AGs’ letter does not distinguish prescription pulse oximeters, which are used in health care institutions or by physician order, from over-the counter (OTC) devices, which are typically used in a home or recreational environment. As described in our previous post, all pulse oximeters are class II devices, but prescription-use-only pulse oximeters require submission and clearance of a premarket notification (also known as a 510(k)) while over-the-counter ones are under enforcement discretion, meaning that no premarket submission is required. Some prescription pulse oximeter devices cleared by FDA specifically describe testing on diverse skin tones in their 510(k) summaries. In fact, in March 2013, FDA published a guidance entitled Pulse Oximeters – Premarket Notification Submission, which provides the following recommendation with respect to in vivo laboratory testing to validate the pulse oximeter SpO₂ accuracy specifications: “Your study should have subjects with a range of skin pigmentations, including at least 2 darkly pigmented subjects or 15% of your subject pool, whichever is larger.” Although agency guidance is non-binding, such a clear indication of accuracy testing expectations indicates that FDA pays attention to the testing methodology and will likely identify any lack of diversity as a deficiency for modern pulse oximeters. Requiring additional warnings in the labeling of pulse oximeters that were not tested on diverse skin tones as the state leaders are urging may, in fact, provide adequate notice and reduce the risks associated with using such devices, but oximeters that did undergo demographically diverse testing should be excluded from any such future requirement.

Of course, OTC pulse oximeters are not subject to the premarket notification requirement, so the current accuracy testing expectations described above would not apply to this subset of devices. FDA could initiate notice-and-comment rulemaking to establish performance standards (pursuant to 21 U.S.C. 360d and 21 C.F.R. Part 861) requiring design and accuracy testing that takes skin tone into account for pulse oximeters and other similar devices that incorporate light-based sensors. A performance standard would apply to all pulse oximeter products, not solely prescription devices, even if FDA continues to exercise enforcement discretion for the premarket notification requirement for OTC devices.

With respect to the AGs’ sixth request, it is highly unlikely that FDA will announce a retroactive requirement for clinical trials involving demographically diverse subjects for all pulse oximeter devices, as this kind of regulatory action would also require manufacturers to recall all pulse oximeter devices currently on the market in order to then “close the data gap” before re-launching them. Presumably, any such requirement imposed by the agency would exclude devices that have already undergone demographically diverse accuracy testing, as discussed above. But highly detailed retroactive clinical trial requirements would be likely to capture almost all pulse oximeters because 510(k) notifications for these devices do not require clinical trials. Even if certain subsets of devices were to be excluded, it would create a massive shortage of prescription-use pulse oximeters in clinical environments. Moreover, this kind of requirement would be likely to apply to only FDA-cleared pulse oximeters, meaning that OTC pulse oximeters with inaccuracies based on skin tone would still be on the market.

Time will tell whether FDA takes seriously the demands outlined in this recent letter and accelerates its action timeline accordingly. We expect the Medical Devices Advisory Committee to publish recommendations relating to pulse oximeters at some point, so it will be interesting to see if any of them align with the points in the AGs’ letter.