If you currently use an iPhone or smartphone app that measures your blood pressure via your finger, take care. According to researchers from the John’s Hopkins University School of Medicine, these smartphone blood pressure apps could provide inaccurate results.
Instant Blood Pressure app
The Instant Blood Pressure (IBP) app,for example, claimed to estimate blood pressure by placing the top edge of the smartphone on the left side of your chest, while placing your right index finger over the smartphone’s camera. Great idea, but leading medics could not find a scientific explanation for how it might work. They believed it could only provide a population estimate based on your age, gender, height and weight (which you programmed into the app) plus your pulse rate which was counted by the phone’s camera.
Researchers therefore compared readings obtained from the app with accurate measurements obtained via validated, automated, upper arm blood pressure monitoring. Blood pressure readings were made for 85 people of whom just over half were known to have hypertension (of whom 91% were on antihypertensive medication).
After sitting quietly for 5 minutes, each volunteer had two BP measurements taken with each device – the upper arm monitor, and the smartphone app. On average, the readings between the two devices differed by 12.4 mmHg for the higher (systolic reading) and by 10.1 mmHg for the lower (diastolic) reading. This particular smartphone app under-estimated the higher systolic reading, and over-estimated the lower diastolic readings.
The researchers state in the journal, JAMA Internal Medicine, that using the Instant Blood Pressure (IBP) app – of which 148,000 units were sold – would falsely reassure 77.5% of people with hypertension that their blood pressure was in the non-hypertensive range. Although the IBP app is now unavailable for sale, it remains installed on many smartphones. Other ‘me-too’ apps are still available.
iPhone and smartphone blood pressure apps may not provide validated results, so if you are using one, and want to continue to do so, double-check your readings against those obtained via an upper arm monitor. Your doctor can check this for you, or you can use a home blood pressure monitor that is validated for accuracy.
Have you tried one of these apps? What was your experience? Please leave a comment below to share your thoughts.
NB This does not apply to non-smartphone devices designed to measure blood pressure at the finger. As with all blood pressure monitors, if you use one of these, check it is properly validated.