Study raises doubts about iPhone-connected blood pressure cuffs

At this week’s American Society of Hypertension (ASH) meeting, two studies will be presented evaluating the use of web-based instructional material and smartphone-connected blood pressure cuffs for the management of hypertension. The findings reported in these two studies are poised to raise doubts about the quality of these tools.

In one study, Dr. Nilay Kumar of the Cambridge Health Alliance evaluated YouTube videos that represented themselves to be educational material related to hypertension. In the other, Dr. Clarence Grim, a healthcare consultant, compared the readings from the Withings and iHealth blood pressure cuffs to manual measurements.

Details on these studies are scant as they are slated to be presented this week at ASH, so we do have to take the reported findings with a grain of salt. [1,2] Nonetheless, these studies do highlight one important fact – in this nascent industry, it is important that clinicians critically evaluate tools that they are considering recommending to their patient.

Ed. Note: In recent articles, we proposed several criteria that clinicians should use when critically evaluating apps for hypertension self management and provided a quick reference on key features of smartphone-connected blood pressure cuffs.

In the evaluation of the Withings and iHealth blood pressure cuffs, a total of 112 readings were taken by the same person using the two smartphone-connected devices as well as manual auscultation. They report that the iHealth device consistently measured higher blood pressures by more than 5 mm Hg while the Withings device consistently measured lower blood pressures as compared to the “gold standard” manual auscultation.

It is worth noting that most blood pressure cuffs simply have to demonstrate that they are “substantially equivalent” to devices already approved/cleared by the FDA before they get on the market. They attest to following certain quality standards. However, no regulatory agency actually checks the devices to make sure they work.

In the 2008 AHA/ASH/PCNA statement on home blood pressure monitoring, third party validation is highlighted as an important consideration in device selection. In our summary of available smartphone-connected blood pressure cuffs, we highlighted the validation status of each of the included devices and it’s worth noting that the iHealth BP5 is among the devices listed by the dabl Educational Trust as independently tested according the European Society of Hypertension protocols (PMID: 23797053).

It is not clear what sort of protocol was used by Dr. Grim and there are potentially many critiques that could be made depending on those details. It is important to remember that this study has yet to be published; as such, we can’t really draw any conclusions at this point. And in the published validation study of the iHealth BP5 from 2013, the mean differences between device & clinician measured blood pressure was -1.21 and 1.04 mm Hg (+/- 5 mm Hg) for SBP and DBP respectively – clearly conflicting with the conclusions of Dr. Grim’s study.

Another important factor we highlighted in our criteria for selecting hypertension self-management apps was the importance of patient-specific “validation.” In other words, taking a specific device and comparing it to in-clinic measurement. As we noted,

In a 2008 Scientific Statement, the American Heart Association, the American Society of Hypertension, and the Preventive Cardiovascular Nurses Association gave a strong endorsement of home blood pressure monitoring (11). In their statement, one clear recommendation was confirming that a patient’s chosen BP cuff is accurate. They additionally provide a suggested protocol to do that. Given that this may not be the first thing that comes to mind for a patient, apps for hypertension self-management should include this recommendation as well.

In addition to this study, Dr. Kumar will present the findings of an evaluation of YouTube videos on hypertension, ultimately finding that one third presented misleading information such as use of supplements or alternative therapy for blood pressure reduction. It can hardly be considered surprising that an unrestricted, completely open video sharing platform would have factually inaccurate information about a specific medical condition. However, given the increasing number of patients turning to the internet for health information, it does highlight the importance of clinicians helping curate and direct patients to reliable content.

Again, it is important to remember that these results are taken from pre-conference materials – these studies have yet to be presented or published. For now, what they should remind all clinicians of is that thoughtful evaluation of web-based and mobile health resources remains crucial in utilizing them appropriately to improve health outcomes.

1. ASH: Accurate HTN Information Available on YouTube. Health eGalaxy.

2. Norton, Amy. Using Internet, Apps to Manage High Blood Pressure Has Dangers: Study. HealthDay.