Does your health monitor have device bias?

Pulse oximeters and other devices used to monitor aspects of our health may work better for some than others.

In recent years there has been an explosion in the number and types of health monitoring devices available in smartphones and fitness apps.

Your smartphone probably tracks the number of steps you take, how far and fast you walk, and how many stairs you climb every day. Some phones track sleep, heart rate, how much energy you use, and even “gait health” (how often are both feet on the ground? How consistent are your steps?). And of course, non-phone wearables and fitness gadgets are available, such as: B. Devices for measuring heart rhythm, blood pressure or oxygen levels. The accuracy of these devices varies – and in some cases, your skin tone can make a difference.

How accurate are health monitors in general?

I know from my experience with hospital monitoring devices that they are not always accurate. False alarms from ECG monitors often result in medical staff rushing into patient rooms only to find the patient feeling fine and surprised by the excitement. A particularly common false alarm is a dangerous and unstable heart rhythm on a continuous heart monitor, which may be due to a patient's movement while brushing their teeth.

High-stakes monitoring devices, such as defibrillators and pacemakers, are extensively tested by their manufacturers and reviewed by the FDA, so their accuracy and reliability are generally quite good.

But what about home health monitoring devices that are intended for consumer use and have not been fully tested by the FDA? Have you ever counted your steps for a few minutes just to see if your phone's count matches? Or climb a few flights of stairs to see if you get full credit for not taking the elevator?

The accuracy of consumer devices partly depends on thisWhatis monitored. For example, one study evaluated the accuracy of heart rate monitors and energy consumption calculators in phones and health apps. Accuracy was fairly high for heart rate (often in the 95% range), but much less accurate for energy expenditure. Accuracy may also vary depending onwhois monitored.

Device Bias: What It Is and Why It Occurs

Although no health gadget is perfect, some users get more reliable results than others. For example, if you wear nail polish, a pulse oximeter — a device that attaches to the fingertip to measure blood oxygen through the skin — may not work well because the polish interferes with the light sensor from working properly. There is a simple solution in this situation: remove the polish.

But in other cases the solution is not easy. We are increasingly recognizing that certain medical devices are less accurate depending on a person's skin color, a phenomenon called device bias.

• Pulsoximeter. Obwohl sie im Allgemeinen als sehr genau angesehen werden und im Gesundheitswesen häufig verwendet werden, ist ihre Genauigkeit bei Farbigen tendenziell geringer. Das liegt daran, dass das Gerät darauf angewiesen ist, dass Licht durch die Haut scheint, um die Farbe des Blutes zu erkennen, die je nach Sauerstoffgehalt variiert. Die Menge an Pigmenten in der Haut kann das Verhalten des Lichts auf dem Weg zu den Blutgefäßen verändern, was zu ungenauen Ergebnissen führen kann.
• Bilirubinmessung bei Neugeborenen. Bilirubin ist ein Abbauprodukt der roten Blutkörperchen. Neugeborene werden auf hohe Konzentrationen untersucht, da dies zu dauerhaften Hirnschäden führen kann. Wenn sie erkannt wird, kann eine Phototherapie (Lichtbehandlungen) dem Baby helfen, das überschüssige Bilirubin loszuwerden, wodurch Hirnschäden verhindert werden. Das Screening umfasst die Untersuchung der Haut und der Augen eines Neugeborenen auf Gelbsucht (eine Gelbfärbung aufgrund von erhöhtem Bilirubin) und einen Belichtungsmessertest, um hohe Bilirubinwerte festzustellen. Aber die Genauigkeit dieses Tests ist bei schwarzen Neugeborenen geringer. Dies ist besonders wichtig, da Gelbsucht bei Säuglingen mit dunklerer Haut schwerer zu erkennen ist und gefährlich hohe Bilirubinwerte in dieser Population häufiger vorkommen.
• Pulsmesser in Smartphones. Laut mindestens einer Studie sind Smartphone-Apps möglicherweise auch weniger genau bei Farbigen. Dies liegt wiederum daran, dass je mehr Hautpigment vorhanden ist, desto mehr Probleme haben Lichtsensoren, Pulsationen im Blutfluss zu erkennen, die Herzschläge widerspiegeln.

Why device bias matters

Sometimes a measurement error has no immediate health consequences. An error rate of 5% to 10% when measuring heart rate may be of little importance. (In fact, you might wonder why anyone would need a heart rate monitoring device when you could simply count your pulse for 15 seconds and multiply it by 4!)

However, pulse oximeter readings are used to decide whether a person needs to be hospitalized, who needs to be admitted to the intensive care unit, and who needs additional testing. If oxygen levels are consistently overestimated in people of color, they may be more likely to be undertreated than others whose readings are more accurate. And that can exacerbate pre-existing disparities in health care.

These examples add to the growing list of biases embedded in health care and other cases where failure to include diverse people has serious consequences. When you use a health device, it's reasonable to ask yourself whether it has been tested on people like you. It is also reasonable to expect that people developing medical and consumer health devices will broaden the demographics of test subjects to ensure that the results are reliable for all users before bringing them to market.

Sometimes a change in technology, e.g. B. using a different type of light sensor can make health-related devices work more accurately for a wider range of people.

Or there is no easy solution and user characteristics must be taken into account in the correct interpretation of the results. For example, a device could offer the user a selection of skin tones that match skin color. Based on extensive data from previous tests on people with different skin tones, the device could then adjust the results accordingly.

The end result

The drive to monitor our bodies, our health, and our life experiences continues to gain momentum. Therefore, we need to thoroughly test and validate health-related devices to ensure they work for different people before declaring them suitable for the general public. An expert panel at the FDA has advocated for better regulation and testing of pulse oximeters to ensure they are accurate for everyone.

Even with the best tests, device bias may not disappear: bodies are different and technology has its limitations. The key is to know it exists, fix what can be fixed, and interpret the results accordingly.

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