You may have heard that you can use your smartphone to monitor your blood pressure. Yes—there is an app for that! In fact, blood pressure apps are proliferating, but can a cell-phone app really monitor your blood pressure in the same way as your doctor’s sphygmomanometer?

It turns out that smartphone apps can help people with high blood pressure, but you need to know which features to look for and which to watch out for. According to a new study, some smartphone apps are making bogus claims that could endanger you.

HOW SMART IS YOUR PHONE?

Researchers searched iTunes and Google Play for popular apps for monitoring blood pressure for Apple and Android phones, respectively. They found 107 apps in total. The popularity of each app was gauged by the number of downloads and user review ratings. After assessing the features provided by each device, they found that, generally speaking, the apps were helpful. The majority (72%) functioned as simple tracking software that allowed users to manually input their blood pressure readings so they could see how readings were improving (or not) over time. Some apps also allowed manual input of information on heart rate, salt intake, weight, exercise and other factors that affect heart health. About one-third of the apps offered general information about high blood pressure, and 22% of the apps helped users remember to take blood pressure medication or check their blood pressure and input data for tracking. And about half of the apps were able to send information entered by the users directly to their doctors’ offices.

The bad news: Seven apps, all for Android phones, claimed to be able to “measure” the user’s blood pressure by reading the pulse of the user’s finger held against the phone’s camera lens or screen. (The two most popular of these apps were the Acc. Blood Pressure Monitor and the Real BP Calculator.) But there is zero proof that this is yet possible. Although the technology for reading finger pulses for blood pressure is in the early stages of development, it is nowhere near ready for consumer use, according to the researchers.

WHAT TO LOOK FOR IN AN APP

The lead author of the study, Nilay Kumar, MD, an instructor of medicine at Harvard Medical School and hospitalist with Cambridge Health Alliance in Cambridge, Massachusetts, has had years of experience working with patients with high blood pressure and is all for use of phone apps that encourage self-management—but, of course, he wants his patients to “do it right.”

“I strongly discourage anyone from ‘measuring’ blood pressure using a smartphone app,” he said. As mentioned, the technology is in the initial stages of development and is not validated (officially approved by the FDA or other authoritative health advocates and policy makers to be accurate and safe).

To get the most out of smartphone blood pressure apps, Dr. Kumar recommends that people with high blood pressure and anyone else who wants to use these apps first purchase a validated cuff-style home blood pressure device, such as those sold by Omron Healthcare. Then choose an app with these features:

  • Tracking of blood pressure. “Blood pressure readings taken in doctors’ offices tend to be higher than normal because patients may be nervous or uncomfortable,” said Dr. Kumar. This may lead to inappropriate diagnosis and treatment. People who use apps to track blood pressure that has been self-measured at home can get a more realistic picture. And apps that track blood pressure are especially useful for patients with uncontrolled or complicated high blood pressure, who often are specifically instructed to self-measure and report the data to their doctors. Before the app era, it was not uncommon for patients to scribble blood pressure information on random pieces of paper that were easily misplaced or later misread, said Dr. Kumar. “An app helps ensure that data is easily retrievable,” he said.
  • Export of information. Apps that not only neatly keep track of blood pressure measurements but can export the information to your doctor are a big plus. Doctors can provide immediate feedback and can be better prepared for when you show up for an appointment.
  • Medication-adherence tools. People with high blood pressure who don’t take their pressure-lowering medication as prescribed have nearly four times the risk of having fatal strokes within two years as people who do take their medication as prescribed. An app that reminds you to stay on top of your meds and to measure your blood pressure and record the numbers can be lifesaving.