Popular blood pressure app has inaccurate readings

Measuring blood pressure? There’s an app for that. Unfortunately, it may not be accurate. A recent analysis of adults in Baltimore found a popular smartphone-based blood pressure app generated a high percentage of inaccurate readings.

The researchers found that 77.5 percent of patients with hypertensive blood pressure levels were assured that their blood pressure was in the nonhypertensive range.

Lead researcher Timothy B. Plante, MD, of the Johns Hopkins University School of Medicine in Baltimore, and colleagues published their results online in JAMA Internal Medicine on March 2. The findings were also presented at the American Heart Association’s Epidemiology/Lifestyle 2016 Scientific meeting in Phoenix.

The researchers examined the Instant Blood Pressure app (IBP; AuraLife) that estimates blood pressure. They mentioned that at least 950 copies of the app were sold for $4.99 apiece on each of the days between June 5, 2014 and July 30, 2015. During that 421-day period, the IBP was one of the top 50 selling apps for the iPhone, according to the researchers. The app was discontinued on July 30, 2015 for an unknown reason.

In this study, the researchers enrolled 85 participants between August and September 2015 who were at least 18 years old from five ambulatory Johns Hopkins sites. Each adult received $5 gift cards for participating.

The IBP required participants enter their date of birth, sex, height and weight, then asked users to place the edge of their phone on their chest while placing their right index finger over the camera lens. The researchers also followed the standard protocol for blood pressure measurements and used calibrated, validated automated sphygmomanometers. They defined hypertensive blood pressure as a systolic blood pressure of at least 140 mm Hg or diastolic blood pressure of at least 90 mm Hg.

Of the participants, 52 percent were women and 53 percent had self-reported hypertension. The mean age was 56.6 years old and their mean body mass index was 27.8 kg/m2.

The mean of the absolute value of the difference in blood pressure readings was 12.4 mm Hg for systolic blood pressure and 10.1 mm Hg for diastolic blood pressure. The researchers said the IBP app underestimated higher blood pressures and overestimated lower blood pressures.

“Our study has both clinical and public health relevance,” the researchers wrote. “While IBP recently became unavailable for unclear reasons, it is installed on a vast number of iPhones; furthermore, several ‘me-too’ apps are still available. Hence, we remain concerned that individuals may use these apps to assess their [blood pressure] and titrate therapy. From a public health perspective, our study supports partnership of app developers, distributors, and regulatory bodies to set and follow standards for safe, validated mHealth technologies.”