Truthfully, the sub-question to this question is what is the difference between a “device” that is ‘nice to have’ and a device that is ‘clinically proven.’ With the explosion of the “wrist-band” generation and the impressive marketing messages on the ample marketing platforms, many of the netizens are confused as to what is their wrist or chest band. Many co-digital junkies compliment the “medical utility” of their bracelet (notwithstanding the brand) and I am always astounded at their shock when I tell them that it is not a medical device but rather at best, a wellness device with no medical or clinical evidence.
Without going into an in-depth and very comprehensive answer, the main difference is practically 3 large letters “FDA” (or the equivalent from other countries like CE, CFDA, KFDA, etc). The world of “wearables” fall into about 4 or 5 categories with wellness, healthcare and dressables being relevant to this discussion. All three groupings have their myriad of apps that promote a healthy living, diet assistance and healthy eating and fitness trackers of different kinds, but very few have medically qualified devices that are approved by a regulatory body. As defined by the FDA, a medical device is “…an instrument, apparatus, implement, machine, contrivance, implant, in vitro reagent, or other similar or related article, including a component part, or accessory which is: recognized in the official National Formulary, or the United States Pharmacopoeia, or any supplement to them, intended for use in the diagnosis of disease or other conditions, or in the cure, mitigation, treatment, or prevention of disease, in man or other animals…”
The question is – do the Fitbit’s of this world measure up to this definition?
Recently, I was discussing with my GP the pros and cons of these devices and she complained that many of her patients are coming to see her based on the results of their wrist-worn fitness trackers. This begs the question – can these devices be used in medical and clinical settings and if yes, for what? Are they accurate enough to measure a patient’s heart rate, O2 stats, sleep cycles, skin temperature or ECG or are they just an indication (quasi-accurate) for us netizens to keep track of our body? While there is no one definitive answer, the medical community is against “self-diagnosis” by these devices as in many cases the false positives are just too high and in the end, nothing is wrong. Moreover, sometimes too much information is not always a good thing.
In a highly none-scientific study, I measured myself using 3 different wrist-worn fitness trackers, 1 HR chest belt and a 12 lead ECG – all the results were different (in comparison with the ECG) – some as much as 34%. So accuracy is as broad as the results themselves. Ryan Kroll and his colleagues from the Department of Medicine and the Department of Critical Care Medicine at Queen’s University, Canada found in a 2016 study that “Personal fitness tracker–derived heart rates were slightly lower than those derived from cECG monitoring in real-world testing and not as accurate as Spo2.R-derived heart rates. Performance was worse among patients who were not in sinus rhythm. Further clinical evaluation is indicated to see if PFTs can augment early warning systems in hospitals.”[1] Even though this study was conducted in an “in hospital” setting, these findings coincide with my “unscientific” study done in my personal gym. While there are a number of other “studies,” none of them are very scientific and are very often industry sponsored so the results are suspect anyway.
So where do we stand? Do we continue to use the wrist based HR monitors or the chest bands or even the 1 or 3 lead ECG’s? While I personally use them, I don’t suggest that many of us use them for a “medical” diagnosis but rather for a trend to see how we are doing from a “wellness” point of view. Using the results of these devices in order to run to the ER or to the clinic is not the correct behavior. If we are interested in a medical analysis, my strong suggestion is to use only FDA-cleared (or similar) devices that have been clinically tested and are accepted by the profession. We are very lucky that we are witnessing an avalanche of new medically rated devices that can support our appetite for bio-feedback and biometrics.
*For the sake of disclosures, I own (and use) today an Apple 2 Watch; Withings Wireless BP Monitor; Polar HR Monitor; Under Armour XXX running shoes. In the field of Apps, I use the Apple Health (I think the best App around); Myfitnesspall; Under Armour Record; Sleep++; Polar Beat.
[1] Kroll RR, Boyd JG, Maslove DM; Accuracy of a Wrist-Worn Wearable Device for Monitoring Heart Rates in Hospital Inpatients: A Prospective Observational Study. J Med Internet Res 016;18(9):e253
