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Wearables are less accurate at tracking people with darker skin tones, new research

A systematic review of existing studies shows that fitness trackers, smartwatches and other wearables are less accurate at tracking the health of people with darker skin tones.


Where does the issue stem from?

The report comes from scientists over at the Univeristy of Alberta in Canada. They’ve concluded that the signalling process does not work as well on those with darker skin. The reasons for this are to do with the way vitals data is captured.

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The main issue is to do with the heart rate sensor. Wearables utilize beams of light to detect the activity of your ticker. Greater light absorption indicates a greater volume of blood flowing through the veins. However this type of tech doesn’t work as well on darker skin that contains more melanin because it absorbs more light.

Another part of the problem may have something to do with algorithms that work with this data. They are typically developed by and tested on white populations. Hence, tweaks that could be implemented to account for those with darker skin are typically not implemented prior to launch.

“People need to be aware that there are some limitations for people with darker skin tones when using these devices, and the results should be taken with a grain of salt,’ said study co-leader Doctor Daniel Koerber.

“Algorithms are often developed in homogeneous white populations, which may lead to results that are not as generalisable as we would like.”

Dr Koerber adds that wearable tech manufacturers should put more effort into emphasising the inclusion of populations of all skin tones. That way algorithms can be better developed to accomodate for variations in innate skin light absorption.


Study findings

The University of Alberta researchers did not conduct an entirely new study. Not in the strict sense. Instead they collated data and performed a systematic review of ten previously published studies. This included info from 622 scientific papers looking at heart rate and rhythm data for consumer wearables. Together, these studies captured information from some 460 participants.

Of the ten, four studies found significant heart rate accuracy issues in darker skinned people as compared to lighter skinned individuals. This included data from chest strap monitors and electrocardiograms which are considered to be more accurate than wrist-based technology. One study did not find any difference, but it reported that there were significantly fewer captured data points in those with dark skin.


Our takeaway

All of this undercores the importance of making sure heart rate tech in wearables meets the needs of diverse populations. This is particularly important as wearables are increasingly looking at more complex heart rate signals to identify possible issues such as tachycardia, bradycardia and atrial fibrillation.

Other studies have reported that this has also been reported as an issue in pulse oximeters. These are devices that measure the oxygen levels in a person’s blood.

Dr Koerber is due to present the findings of the study at the American College of Cardiology’s annual converence in Washington DC in April.

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