An accurate blood pressure reading is one of the most important screening tools doctors have for diagnosing patients. So it would make sense that a blood pressure reading mobile application might be a perfect tool for doctors to ensure patients can monitor their blood pressure on the go (if it is necessary).

But just because an idea sounds good does not necessarily meant that it will be executed perfectly. This is what a new study investigates, suggesting that a new—and quite popular—blood pressure application might not present the most reliable data.

According to researchers, the Instant Blood Pressure app from AuraLife might give erratic results that could lead the user to believe they have normal blood pressure when they really do not. The device, of course, was designed to estimate blood pressure by placing the edge of a smartphone or a tablet on the part of the chest where the heart is located. The user also puts their right index finger over the device’s camera lens.

New Blood Pressure Monitoring AppResearchers at John Hopkins University, however, say that 80 percent of patients with blood pressure at 140/90 received normal blood pressure readings. Obviously, this would put the vast majority of users at great risk.

Dr. Timothy Plante, of Johns Hopkins University, laments, “If Instant Blood Pressure worked, it would be a revolutionary new technology that would allow for low-cost screening and management of hypertension among smartphone users.”

The lead study author goes on to say that erroneous blood pressure readings should be of high concern, of course, because hypertension is generally considered a “silent killer,” claiming lives after following an asymptomatic path that can result in various other serious health conditions like heart disease, kidney disease, and eventually even stroke.

Along with study co-author Seth Martin, Plante also comments that it is yet unclear just how the app actually arrives at its blood pressure reading. The pair suggest, through the study, that instead attempting to get an accurate blood pressure number, the app uses an estimate derived from analyzing population statistics in terms of the user’s sex, age, weight, height, and heart rate.