Wearable technology has been all the rage for the past few years, with a prediction of 245 million devices selling in 2019. Fitbit, Apple, Nike, Garmin, and even UNICEF have all created wrist-worn technology built to get people off their butts and into shape. These fitness trackers calculate your steps taken, calories burned, miles walked, stairs climbed; heck, they’ll even tell you how well you slept last night. But a recent study urges caution in taking those statistics as gospel, because the health information they reveal may not be good enough to rely on.

The study, published in PLOS Medicine and conducted by Lancaster University, the University of the West of England, and Nottingham Trent University, aimed to see how reliable the devices actually were at monitoring health. They found that, contrary to the marketing of wearables for improving health and fitness, there really isn’t much evidence regarding the long-term health benefits of keeping one strapped to your wrist. The researchers noted, however, that those with conditions like diabetes or cardiac disease would benefit a little more from using the devices.

"For chronic conditions, wearables could effortlessly provide detailed longitudinal data that monitors patients' progress without the need to involve more sophisticated, uncomfortable, and expensive alternatives,” said co-author Dr. David Ellis of Lancaster University, in a press release. “For instance, it is possible to identify the severity of depressive symptoms based on the number of conversations, amount of physical activity, and sleep duration using a wearable wristband and smartphone app."

On top of monitoring depression, wearables could also help monitor sleep apnea, a sleep disorder in which breathing repeatedly stops and starts; track the possible onset of Parkinson’s using microanalysis of body movement data; and provide instant feedback as a platform for at-home management of long-term medical issues, like obesity, anxiety, panic disorders, PTSD, and asthma.

That said, for those who don’t suffer from chronic conditions but believe getting a wearable leads to better health, the researchers say there isn't much scientific proof (in the way of randomized, controlled studies) out there to support the marketing hype behind these devices. The researchers described wearables as “a solution in search of a problem.”

This lack of proof over the efficacy of fitness trackers also led researchers to describe the “gray area” that exists regarding user safety. They say an over reliance on wearables could potentially give users a false sense of security about their health — or even lead them to incorrectly self-diagnose some medical condition. Since one wearable might not be as beneficial to one person as it is to another, the researchers recommend more studies be done to consider the complex relationship between wearable devices and individual users.

The future of wearables in the health care sphere is murky at best as they may be unreliable and potentially misleading. When compared to health apps on smartphones, which go by a standardized tracking code, "various wearables for tracking physical activity showed large variations in accuracy between different devices — with error margins of up to 25 percent," the researchers wrote. Developers of wearables need to “open access to their data collection practices, analysis methodologies, and measurement concerns,” the researchers concluded. “This would address not only the issue of wearables’ reliability but also secondary concerns relating to data storage and [patient] privacy.”

Even though most people dump their fitness tracker after six months of use, there’s huge potential for wearables to become a major asset in the health care market, while providing patients and professionals quantified results that’ll help diagnose seen or unseen medical issues.

Source: Piwek L, Ellis D, Andrews S, Joinson A. The Rise of Consumer Health Wearables: Promises and Barriers. PLOS Medicine. 2016.