FULL CLAIM: Blood pressure tracking apps can replace a cuff
REVIEW
High blood pressure is a major cause of premature death and affects over one billion people worldwide. Blood pressure is typically measured using a cuff around the upper arm. The cuff is inflated to stop blood flow and slowly deflated to detect the pressure once the blood flows again. The American Heart Association has published instructions on how to take an accurate reading, including resting beforehand, sitting upright, and using a properly calibrated and validated device.
Blood pressure levels are measured using two numbers, the systolic and diastolic pressures, which respectively refer to the maximum and minimum pressure recorded as the heart contracts and relaxes. A systolic pressure over 130 mmHg or a diastolic pressure over 80 mmHg is considered to be hypertension (high blood pressure).
A widely-shared Facebook post featured a video of someone dressed as a doctor pushing aside a blood pressure cuff and giving it a thumbs down, before holding her finger to the camera of an iPhone with an app appearing to display live measurements of her heart rate, blood pressure, blood oxygen, and temperature. The post encouraged viewers to download the app Blood Pressure-Monitor Tracker.
The description for the app in the App Store says that it “is like a complete blood pressure monitor”. Both the Facebook post and the description in the App Store misleadingly suggest that the app can measure blood pressure. However, according to the app developer, the blood pressure values needed to be entered into the app manually by the user. This was not clearly explained in the app description, leading to a negative review from a user, at which point the app developer responded to explain the process.
Despite the way it was shown in the promotional Facebook post, there is no indication that the app is able to to measure blood pressure. Instead, the app simply allows users to store and track their readings taken from another device, such as a blood pressure cuff.
Blood pressure monitoring should only be done with validated medical devices
There is a notable history of apps making unsupported claims that they can accurately measure blood pressure from a smartphone.
In 2016, researchers from the Johns Hopkins University School of Medicine examined the accuracy and precision of one of these popular apps called “Instant Blood Pressure”[1]. The app was available for over a year and regularly featured in the top 50 best-selling iPhone apps[1].
The researchers measured the blood pressure of 85 people using the app and a calibrated, validated blood pressure cuff (sphygmomanometer). The results showed that the app tended to underestimate high blood pressure and overestimate low blood pressure. As a result of these errors, the app missed about four-fifths of people with hypertension, falsely reassuring them that their blood pressure was in the healthy range.
By the time the study was published, the Instant Blood Pressure app had been removed from the Apple App Store and the Google Play store. However, the researchers cautioned that there were several similar apps still available.
Those considering using these unvalidated apps should keep in mind that proven blood pressure monitors for routine check-ups and self-monitoring are under regulatory oversight to ensure that they work as intended. Such monitors are categorized as Class II and Class IIa medical devices by the U.S. Food and Drug Administration and the European Commission, respectively. Any effective blood pressure monitor would be expected to reach these standards.
The American Heart Association recommends cuff-style monitors, as they are more reliable than wrist or finger monitors, providing that the cuff is the correct size. It also suggests having a healthcare professional check that the monitor is being used correctly and gets the same results as the clinic’s equipment.
Recent research found that the majority of arm cuff monitors sold on Amazon had not been validated by independent testers to confirm their accuracy[2]. Databases of validated blood pressure monitors are available for the U.S. and worldwide.
Basing healthcare decisions on an unvalidated and unregulated app can be dangerous. Any concerns about blood pressure, or about taking medication for hypertension or hypotension (low blood pressure), should be discussed with a qualified healthcare professional.
REFERENCES
- 1 – Plante et al. (2016) Validation of the Instant Blood Pressure Smartphone App. JAMA Internal Med.
- 2 – Picone et al. (2023) Availability, Cost, and Consumer Ratings of Popular Nonvalidated vs Validated Blood Pressure–Measuring Devices Sold Online in 10 Countries. JAMA.
