Wearable Medical Devices: What You Need to Know

Jackie Liu, National Center for Health Research


Wearable medical devices such as the FitBit or other SmartWatches are electronic devices that you wear to track personal health data, such as how many steps you have taken in a day or your heart rate. As of 2020, 30% of American adults use a wearable medical device. Among the users, almost half use a wearable medical device daily.1 This article will explain what wearable medical devices are, how they are used, how the FDA regulates them, and the benefits and risks of using these devices.

How are wearable medical devices used?

Wearable medical devices can be divided into two categories: personal use and clinical use. Personal use wearable medical devices are used by an individual to track their own health data, such as monitoring their heart rate during a workout. People tend to use these devices in order to improve fitness or lifestyle, not because of medical necessity. Clinical use wearable medical devices, such as blood sugar readers, are used by healthcare providers to monitor and better understand a patient’s health status.

Personal Use

Personal use wearable devices include fitness trackers such as Fitbit or the Samsung Galaxy Watch. There are also more specialized personal use wearable devices like the Omron HeartGuide blood pressure cuff and the Ava wearable to track fertility. These devices collect health data from the wearer and send that data to the person’s smartphone to be stored and analyzed.

Fitness trackers can help people who want to improve their health through lifestyle changes. An example of such trackers are pedometers, which track the number of steps. Some research has found that pedometers help increase physical activity. For example, a 2007 review of 26 studies on pedometers used in an outpatient setting (rather than in the hospital) found that these devices increase daily physical activity by 27% over the participants’ initial step counts.2  And a 2019 review of 35 studies of patients with chronic cardiometabolic disease found that wearing a fitness tracker that counts steps helped people increase the number of steps they took per day by a median of 2,592 steps. Researchers in both studies concluded that since fitness trackers allowed users to track and quantify their physical activity, that encouraged wearers to lead a more active lifestyle.3

Clinical Use

Healthcare providers sometimes give wearable devices to patients with chronic diseases in order to monitor them. For example, a 2016 study gave 400 patients a blood pressure cuff to monitor their blood pressure for 90 days. These data were collected in an app and sent to the healthcare provider’s office monthly so providers could respond to changes in patients’ blood pressure by altering medication dosages and other interventions. Patients also received monthly reports of their blood pressure measurements. Researchers found that 71% of participants using the cuff were able to achieve their target blood pressure. In comparison, only 31% of participants under usual hypertension care were able to achieve target blood pressure. Both the cuff and its app gave providers a better sense of a patient’s blood pressure over time, allowing them to more accurately adjust a patient’s hypertension treatment regimen. The app also gave patients immediate alerts if their blood pressure was too high as well as tips to lower their blood pressure,such as through diet and exercise. This, in turn, allowed patients to lower their blood pressure to a normal range.

Risk

While wearable medical devices can enhance a person’s understanding of their body and a doctor’s understanding of their patient’s health, they also pose some risks. The combination of plastics and metals used to construct wearable medical devices a person wears can cause skin irritation and even chemical burns.5 Many consumers use these medical devices to track their health status by monitoring heart rate, blood pressure, and more. However, several experts have called the accuracy of this data into question. A 2020 review of the literature on medical device data accuracy found that simple devices such as pedometers (which count steps) do not accurately measure step count. Pedometers are less accurate when placed on the wrist or hip in comparison to when placed on the ankle. Pedometers can also miscount steps if the person walks too slow or has an imbalanced gait when walking.6 In fact, some small studies suggest that popular pedometers such as the FitBit can substantially undercount steps, with one study averaging a Fitbit undercount of 55 steps during a 5 minute walk on a treadmill.7, 8 Inaccurate health data can lead consumers to make inappropriate health decisions based on seemingly sound information.

Accurate or not, another risk to consider is who is regulating medical device data. While the FDA regulates medical devices, the responsibility of protecting the privacy of the data collected by these technologies. lies with the Federal Trade Commission (FTC). The FTC has the authority to protect consumers from corporate acts that are unfair or deceptive.9 While this sounds good in theory, in practice it has not proven to be an effective measure of protection to consumers.10 For example, in 2021, 61 million health records from FitBit and Apple Watch users were leaked in a data breach. Data such as the user’s name, gender, age, and geographic location were all exposed, leading many to call for increased data security for wearable devices.11

Some publications support getting the government involved in regulating health data. Staff at The Lancet and The Financial Times co-authored a report titled the Commission of Governing Health Futures.12 They urge countries to strengthen public safeguards on the use of digital health data because they are concerned that such information could be shared or sold to private companies without the knowledge of patients. This could result in sensitive patient data, such as medical condition, age, or weight, being given to corporations for them to profit off of, all without patient consent. By increasing government oversight on how health data is secured, experts hope that patients will not need to live in fear of their personal information being shared or sold unbeknownst to them.

There is also concern about the algorithms used in medical devices because they could be biased or inaccurate, resulting in discrimination in patient care.13 For example, a 2020 study examined how a disproportionate percentage of men or women would affect how AI algorithms diagnose medical images (i.e. X-rays, CT scans, etc.). Researchers found that if an algorithm was trained with a dataset that included only a small number of female patients, it would be more likely to misdiagnose a female patient.14  A 2020 study found that pulse oximeters, devices that are used to measure blood oxygen levels, were 3 times more likely to miss low blood oxygen levels in Black patients when compared to white patients.15 From these results, researchers emphasized the need to consider gender, race, and other forms of bias when creating medical AI algorithms.

Regulation

The FDA is responsible for regulating medical devices. Some medical devices are considered “high-risk” and require clinical studies before they can get approved by the FDA. High-risk devices, such as pacemakers or an artificial heart, are defined by the FDA as sustaining or supporting life, are implanted, or present potential unreasonable risk of illness or injury, but not all high risk devices are required to be proven safe or effective.16 Medical devices that the FDA considers “moderate-risk” do not need to submit data on safety or effectiveness, and are rarely required to submit data from clinical trials.  They are not approved by the FDA but are instead labeled as “FDA cleared.” Wearable medical devices are considered moderate risk. A moderate-risk medical device is defined as having some risk that must be regulated in order to prevent harm to the user or others. In order to qualify as FDA cleared, a wearable medical device must either encourage healthy behaviors without referencing any particular disease/condition, or promote healthy lifestyle choices that have been shown through data to improve health or quality of life.17, 18 

Of the previously discussed examples of wearable personal medical devices, all were FDA cleared because they are considered as health-promoting tools that are moderate-risk and non-invasive. But even with this status there is some nuance. The FitBit device itself only needed clearance, but its app to track atrial fibrillation needed FDA approval.19 

In the above examples, medical companies went through the FDA approval/clearance process so they could advertise their products as medical devices that track health data. This is not always the case. Sometimes the FDA has to send warning letters to companies that advertise their product as a medical device but failed to seek approval or clearance from the FDA. In 2021, the baby technology company Owlet stopped selling its Smart Sock–a device that monitors a baby’s vital signs–after receiving a warning letter from the FDA. The Smart Sock did not have marketing approval or clearance from the FDA, but was being advertised by the company as a diagnostic tool.20 

The bottom line

Wearable medical devices are popular in the U.S. and consumer use is expected to rise even more in the future. These devices can be useful in improving daily physical activity and have possible applications in clinical settings for monitoring and diagnosing patients. Still, wearable medical devices do carry risks such as skin irritation, inaccurate medical data, privacy breaches, and biased algorithms. While devices are regulated by the FDA, the health data that they produce and emerging AI technologies used for diagnostics are currently under-regulated in the U.S. This means that using these devices carries some risks for the consumer.

All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.

The National Center for Health Research is a nonprofit, nonpartisan research, education and advocacy organization that analyzes and explains the latest medical research and speaks out on policies and programs. We do not accept funding from pharmaceutical companies or medical device manufacturers. Find out how you can support us here.


References:

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