A new study has found that wearable technology can be used to tell if someone is falling ill (New Scientist, 2017).

Stanford University geneticist Michael Snyder wore eight fitness tracking devices every day for two years to see if there were any differences between them (Scientific American, 2017). He and several colleagues also put the devices on sixty volunteers to check if his results were representative of other people, which they were.

The researchers released their results in a new study published online yesterday in PLoS Biology, which concluded that wearable devices can reveal personalised circadian rhythms, track changes in specific environments such as airplane cabins during flight and combine biosensor information with medical measurements to help detect when wearers are falling ill. The research team developed a computational algorithm that can analyse signals from the devices to reveal very early signs of trouble, including differences in insulin sensitivity, which may help diagnose type 2 diabetes.

Michael Synder said “Too much of the time we spend time measuring people when they’re sick. What we really want to understand is what does it mean to define a healthy state, then quickly identify deviations from that state [when someone is falling ill]. I think the wearables are going to be a big part of that.”

Michael Snyder and his colleagues collected more than two billion bits of data from the volunteers, who wore as many as seven wearable devices each day for up to eleven months, to track multiple metrics and see if some devices were more accurate than others. They gathered information on weight, heart rate, blood oxygen, skin temperature, activity and calories expended. The participants, some of whom knew they were diabetic, also submitted to regular lab tests of their blood chemistry and gene expression as well as other measurements. Some subjects tracked during airplane travel showed a consistent drop in their oxygen levels above 8,000 feet in elevation, possibly explaining why some people start to feel sleepy early on during a flight. MichaelSnyder found that his own oxygen levels tended to rebound by the time he landed.

Michael Synder said “Once these wearables collect enough data to know what your normal baseline readings are, they can get very good at sensing when something’s amiss. We think that if your heart rate and skin temperature are elevated for about 2 hours, there’s a strong chance you’re getting sick.” He said continuous tracking of a person’s vital signs is more informative than having a doctor measure them once a year and comparing them with population averages, pointing out “Heart rate, for example, varies a lot so population averages don’t tell you much.

The team is now hoping to build algorithms that will enable smartwatches to notify wearers when they might be falling ill. Michael Synder said “I’m predicting that your smartwatch will be able to alert you before you get sick, or confirm that you’re sick if you’re feeling a bit off. If your watch says you’re getting something, you’ll know to go lie down instead of going out drinking and dancing.”

Michael Snyder tracked himself getting sick several times. Once, on a flight to Norway, his devices picked up something strange. His blood oxygen level did not bounce back as usual. Then they showed he had developed a low-grade fever. he had been in a possible tick habitat in Massachusetts a week earlier, so he asked a doctor to test him for Lyme disease. He was diagnosed at the earliest stage of the disease, when treatment has the best chance of success. Without the tracking he would probably have ignored the signs until his infection was more advanced.

The devices also accurately tracked the return of Michael Snyder’s insulin sensitivity, which he had kept under control by exercise. What he saw in himself was similar to what the researchers detected in other study volunteers, including changes in insulin sensitivity and the early indication of illness. Michael Snyder compares the information from the sensors with seeing the “check engine” light in a car. He said “You might hear some knocks” in the engine beforehand, tipping you off to a potential problem, but “it’s nice to see a little light when something’s not right.”

He believes the devices should be useful for tracking and better understanding the physiological effects of ageing. He said “We will see personal markers of aging as we follow people very closely. Understanding your baseline while you’re healthy is really, really important.”

Michael Snyder hopes researchers will try to figure out which wearable devices are best at health detection, so no one needs to wear the eight devices that he straps on every day. His team counted more than five hundred different devices, offering different types of data, the last time they checked in the summer of 2015.

Peter Rasmussen, medical director for distance health at the Cleveland Clinic, agrees the full potential of wearable devices has yet to be realised. He said “We’re really at the embryonic stages of these things.” He hopes that in the next few years data from wearable devices can be integrated into a person’s medical record, allowing health care providers to monitor the individual continuously over time. Then, he said, “we can begin to apply some higher-level artificial intelligence to machine learning to begin to look for trends we don’t even know exist. We may find wonderful things that we can [use to] intervene on patients before they are actually ill.”

“It’s really exciting to consider how much earlier we could intervene to prevent somebody becoming seriously ill,” said Meredith Makeham, chief medical adviser to the Australian Digital Health Agency. But she warned that patients and doctors should be aware of a device’s error rate, and whether it is being used in the recommended way.

Nathan Pinskier, chair of the eHealth committee of the Royal Australian College of General Practitioners in Melbourne, said the technology could lead to unnecessary worry. He said “One of the major things we manage in general practice is anxiety – you get a lump or you feel a bit unwell, and you feel anxious about it. There’s the risk that people will rush off to their GP because they have all these unexplained findings.” He added that a person knowing they’ll get sick won’t help avoid it “If you’re going to get the flu, you’re going to get the flu.”