Not all mHealth apps are made equal. With more than 160,000 such titles now available for download, it’s only natural that some are working better than the others.

One of the apps that promised to “deliver the goods,” Instant Blood Pressure (IBP), is not doing so, according to researchers from the Johns Hopkins University School of Medicine and Pomona College. Developed by digital health startup AuraLife, said app was downloaded nearly 150,000 times, promising accurate blood pressure measurements that rely only on iPhone’s built-in sensors. It prompted users to place the upper edge of their smartphones on their chest while covering up the camera with their right index finger.

Instant Blood Pressure was available in Apple’s AppStore between June of 2014 and July of 2015.IBP was available in Apple’s AppStore between June of 2014 and July of 2015 with a price tag of $4.99; and during that time – it was a top 50 best-seller for 156 days.

After testing IBP on 85 participants, researchers have found that the app had a tendency to inform users that their blood pressure was in the normal range when it was actually quite high. Their study was published in the medical journal JAMA Internal Medicine.

“The low sensitivity for hypertensive measurements means that approximately four-fifths (77.5%) of individuals with hypertensive BP levels will be falsely reassured that their [blood pressure] is in the non-hypertensive range,” researchers wrote. “Our study has both clinical and public health relevance. While IBP recently became unavailable for unclear reasons, it is installed on a vast number of iPhones.”

Responding to a request for comment from Fortune, Auralife’s co-founder and CEO Ryan Archdeacon said:

We were shocked to have identified critical deficiencies and inaccuracies in the study control design and data analysis that cause it to inaccurately portray the performance of Instant Blood Pressure. We have our own data.

We welcome third party researchers taking an active interest in assessing our technologies. Further, we believe open discussion with researchers is important and we welcome the opportunity to provide our feedback.

With that said we do believe that three critical items need to be taken into consideration. These concerns were shared with the authors late on March 1st and on the morning of March 2nd conversations between AuraLife and the authors’ team were initiated. Those conversion are ongoing and we are awaiting the Plante et. al. team’s response.

IBP is by no means the only app the makes promises it can’t deliver. There are similar apps still available for download and it remains to be seen whether FTC will take action against their makers. For what it matters, the Commission did react in the past.