Blood pressure readings using public kiosks or smart phone apps: Caveat emptor (for now)

Hypertension remains a large public health issue despite availability of multiple generic antihypertensive drugs, and blood pressure (BP) control remains poor. Patients are encouraged to play a larger role in their BP control and home BP monitoring is encouraged. Access to home monitors is often problematic due to cost and convenience, resulting in patients either checking BP at public BP kiosks or by downloading apps that measure BP through smartphone technology.

BP kiosks are “stations” where BP is automatically assessed by an automated BP device that is placed in a public place such as a pharmacy or a supermarket. They are designed to be operated by the patient independent of a healthcare professional. The issues with these devices are as follows: most devices are not standardized and do not meet the requirements of the Association for the Advancement of Medical Instrumentation; appropriate cuff sizes are often unavailable, with many kiosks having only one size cuff, leading to falsely high readings if the cuff is too small and falsely low readings if the cuff is too large; and the setting in which the kiosks are placed are usually undesirable, as BP should ideally be checked in a quiet environment after 5 minutes of resting with the person sitting with the arm supported at heart level and the feet on the floor. Because the ideal conditions are usually impossible to achieve and the kiosk monitors are not standardized or calibrated, both the American Society of Hypertension and the World Hypertension League recommend against using these kiosks to check BP.1, 2

More than half of adults in the United States now use a smartphone.3 Use of smartphone mobile health apps to measure BP has the ability to impact BP control with improved access to BP monitoring. Many mobile health apps have been developed both for Android (managed by Google) and iPhone (managed by Apple) users. These BP measurement apps range from free to $4.99 and vary in what they offer, ranging from apps that simply make the phone itself a measurement device, to apps that facilitate via bluetooth technology the transfer of BP data from a commercial BP measurement device to the phone itself, to apps that record longitudinal BP measures and provide therapy recommendations based on standard BP guidelines.

A recent study from John Hopkins University School of Medicine evaluated the Instant Blood Pressure app (IBP; AuraLife, Newport Beach, CA, USA) for accuracy and precision.4 This app estimates BP using a technique in which the top edge of the smartphone is placed on the left side of the chest while the individual places his or her right index finger over the smartphone's camera.

Enrolled patients were at least 18 years old from five outpatient sites. The research staff were trained to measure BP according to manufacturer guidelines using the IBP app. Standard BP measurements were also performed following a standard protocol using a calibrated, validated automated sphygmomanometer (Omron 907 or 907XL, Omron Healthcare, Kyoto, Japan). The order of BP measurement was random. Participants were required to sit quietly for 5 minutes and then had two sequential BPs taken by each device, separated by 60 seconds.

A total of 85 participants were enrolled, of which 52% were women, with a mean age of 57 years and a mean body mass index of 27.8. A total of 53% of patients self‐reported hypertension and 91% were taking antihypertensive medications. The mean of the absolute values of the difference between IBP and standard BP were 12.4 mm Hg for systolic BP and 10.1 mm Hg for diastolic BP. In addition, IBP underestimated higher BPs and overestimated lower BPs, with systolic BP readings within 5, 10, and 15 mm Hg of the standard BP measurement 24%, 44%, and 59% of the time, and diastolic BP readings were within those same parameters 26%, 48%, and 70%, of the time, respectively. Almost 80% of individuals with hypertensive BP levels would be falsely reassured that their BP is in the nonhypertensive range by using this app. from the The IBP app sold more than 148 000 units but the measurements were highly inaccurate. This app is now unavailable but there are similar apps that remain available, including Blood Pressure Pocket and Quick Blood Pressure Measure and Monitor.

Although these apps theoretically can improve out‐of‐office monitoring, there are several problems including accuracy,4 validation, and standardization, and none of these apps have been cleared by the Food and Drug Administration. Less than 5% of BP apps for smartphones were developed with academic input, and existing literature suggest they perform poorly.3 There are also issues of data security and confidentiality, data falsification, and incorrect placement.5 These apps are also designed to be used in diagnosis and management of disease but they need to be tested to assess whether use of these devices improve health outcomes. Without longitudinal data showing the value of these apps or kiosks in managing BP and preventing target organ damage, practitioners cannot provide sensible, informed advice to patients regarding these devices and their use should not be encouraged.6

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Cohen DL, Townsend RR. Blood pressure readings using public kiosks or smart phone apps: Caveat emptor (for now). J Clin Hypertens. 2017;19:946–947. 10.1111/jch.13013