New Approaches to Evaluating and Monitoring Blood Pressure

Abstract

Digital health innovations for hypertension include cuffless blood pressure sensors, wireless smartphone-enabled upper arm blood pressure monitors, mobile applications, and remote monitoring technologies. Wearable trackers have drawn interest from medical professionals and patients alike. They have the potential to improve hypertension control and medication adherence through easier logging of repeated blood pressure measurements, better connectivity with health-care providers, and medication reminder alerts. With increasing emphasis on home and ambulatory blood pressure monitoring to confirm hypertension prior to treatment, such devices also can help improve the diagnostic landscape. However, privacy, accuracy, and cost concerns have prevented widespread clinical uptake. To foster implementation, device designers and clinical researchers should collaborate on development of rigorous clinical trials that test cardiovascular outcomes associated with emerging technologies. We review the current literature on mobile health technologies and novel diagnostic and management protocols and make recommendations on how to incorporate these innovations into practice.

Introduction

The model of office-based hypertension diagnoses and management is changing with the emergence of mobile health care (mHealth) and increasing acceptance of home blood pressure monitors as a diagnostic and monitoring tool [1–3]. New bio-medical technologies can monitor heart rate, blood pressure, activity level, and various other indices of health. Mobile apps simplify the logging and trending of blood pressures, sync with electronic health records, and allow for better remote monitoring by health-care providers. Developers and early adapters are optimistic that these innovations will lead to cost savings and improved chronic disease management, while reducing the care burden of physicians. Venture funding of digital health companies reached $4.5 billion in 2015 and wearable technologies are likely to become more ubiquitous [4]. However, current clinical practice still relies heavily on traditional office-based blood pressure monitors and protocols, due in part to uncertainty regarding the reliability and safety of newer technologies.

The most recent hypertension guidelines have deemphasized office-based hypertension diagnoses and recommended home blood pressure and ambulatory blood pressure monitoring prior to starting antihypertensive treatment [5, 6]. Despite evidence-based validation protocols, hypertension guidelines have yet to address emerging wearable technologies [7, 8••]. Given the widespread enthusiasm for disease self-management, it is critical to further evaluate the efficacy, safety, and privacy concerns of new technologies in rigorous studies. We review the current literature on mHealth technologies and novel diagnostic and management protocols and make recommendations on how to incorporate these innovations into physician practice.

Device Innovation

The major device innovations for out of office use include wireless upper arm blood pressure cuffs and cuffless devices (Table 1). Wireless upper arm cuffs are automated oscillometric devices that sync via bluetooth technology to a computer or smartphone. These function like automated devices in current clinical use by recording vibrations in the arterial wall to establish systolic and diastolic pressure. Blood pressures are automatically logged and saved. Many are user friendly and can improve the accuracy of recording by avoiding transcription errors, while saving time. However, most are marketed between US$100 and US$140, which may be prohibitory for some patients. Additionally, these devices require some basic knowledge of mobile and computer use, including the need for regular software updates, and depend on wireless connections—a requirement that may not always work flawlessly. One recent study found 28 % of users experienced device malfunctions that required technological assistance [9].

Table 1.

New technologies for blood pressure monitoring and management

Device	Method	Benefits	Drawbacks	Notes
Hypertension apps for mobile devices	Smartphone applications allow for manual or automatic BP logging	May increase patient engagement and self-management, may be helpful when there is a long latency to follow-up visits	Poorly regulated, most do not share data with physician offices, may encourage unwarranted self-titration of medication or provide factitious blood pressure measurements	Only 3 % of reviewed hypertension management apps were developed by health-care agencies [19••]
Self-use wireless upper arm blood pressure monitors	Blood pressure devices that can upload data to mobile phones or computers	May increase willingness to perform frequent blood pressure checks, may make physician oversight easier	Cost, bluetooth technology often requires troubleshooting	Examples of validated devices include Withings, QardioArm, iHealth [29]
Text messaging	Sends messages to remind users to take medication	Improves medication adherence	Cost, requires physician oversight	Home blood pressure monitor measurement self interpretation through text messaging [30]
Remote monitoring	Provides feedback on blood pressure measurements	Useful in resource limited areas	Cost, requires physician oversight	SIMCARD study achieves lower systolic blood pressure using smartphones and community health workers [27]
Cuffless blood pressure devices	Measure blood pressure using sensors	Less bothersome for patients than devices with cuffs, particularly when needing measurements during sleep	Cost, insufficient accuracy	Examples that are FDA approved include Sotera, Somnotouch-NIBP

A second group of emerging devices is cuffless and applied to the wrist or finger. Traditional teaching has been that blood pressure monitors should be applied close to the heart, specifically the upper arm, to be most accurate [10–12]. Similar to fitness trackers, these new wearable devices track vital signs via optical sensors. These wrist and finger sensors use beat-to-beat variability to compute systolic and diastolic readings. Using computerized mathematical modeling, corresponding systolic and diastolic blood pressures are computed and data are indicated on some form of visual interface. For instance, one such device, Somnotouch-NIBP, uses finger photoplethysmography and three ECG leads connected to a watch-like control unit to obtain systolic and diastolic blood pressure via pulse wave velocity measurements [13]. The interval between the R wave on the ECG and the arrival of the corresponding pulse wave from the finger is recorded and translated into blood pressure readings. However, many devices that utilize pulse wave velocity require initial calibration using an oscillometric brachial cuff, making the accuracy of the technology somewhat dependent on traditional methods.

The benefits of these blood pressure sensors include the ability to monitor continuously and avoid sleep-disrupting cuff inflations when measurements are required at night. Additionally, their greater ease of use makes them particularly attractive in the elderly or immobilized patients that may be most vulnerable to overtreatment and undertreatment with an-tihypertensives. The trade-off for this convenience lies in the accuracy of the devices. Although many wireless sensors have been validated and FDA approved for clinical use, measurements can vary as much as 20 mmHg from blood pressures derived using brachial cuff. When they are inaccurate, they tend to underestimate blood pressure [12] particularly at the higher end of the scale (i.e., greater than 160 mmHg systolic) [14••].

Other cuffless devices include apps that work by application of a finger to the touch screen of the smartphone. Several of these are listed in Table 2 and are among the highest rated apps for blood pressure; however, none have been scientifically validated or recommended for clinical use. To the contrary, as evidenced by a study of Instant Blood Pressure (AuraLife), an app that was purchased by nearly 150,000 individuals, such technology may be highly inaccurate, with readings that are within 15 mmHg of brachial cuff measured systolic and 10 mmHg diastolic blood pressures only 59 and 70 % of the time, respectively [15].

Table 2.

Top-rated iOS and Android smartphone applications for hypertension

Name	Company	Functionality	Processing method	Cost (US$)	Last update
iOS applications
Smart Blood Pressure (Smart BP) BP Tracker	Evolve Medical Systems, LLC	BP, heart rate (HR), weight	Manually logs, syncs with many commercially available devices via HealthVault including A&Da, Omrona, Withingsa, and QardioArma	$1.99	Feb. 27, 2016
Blood Pressure Monitor—Family Life	Taconic System LLC	BP, HR, weight, height, medication tracking, and correlation with BPs	Manual logging	$2.99	Nov. 20, 2015
Qardio Heart Health, Weight and Blood Pressure Monitor	Qardio, Inc.	BP, HR, weight, height	Syncs with QardioArma wireless blood pressure monitor and/or QardioBase smart scale for weight measurement	Free	Feb. 2, 2016
Blood Pressure Companion Free	Maxwell Software	BP, HR, MAP, weight	Manual logging	Free	Oct. 29, 2015
Heart Star Blood Pressure Monitor	Little Green Software	BP	Syncs with bluetooth-enabled monitors	Free	Dec. 1, 2015
Blood Pressure Lite	Codulis	BP	Manual	Free	Mar. 3, 2016
Blood Pressure–BP Tracker for Hypertension Management	Codulis	BP (with improved graphics/charting from lite version)	Manual	$4.99	Mar. 3, 2016
Hello Heart	Hello Doctor, Ltd.	BP, HR, weight; reminders and easy sharing of results with doctor, easy import of lab results, HIPAA compliant	Manual entry, syncs with many devices including apple watch	$59.99	Dec. 6, 2015
Blood Pressure Monitor—Family Lite	Taconic System, LLC	BP, HR, weight, medication	Manual	Free	Nov. 20, 2015
IBP Blood Pressure	Leading Edge Apps, LLC	BP	Manual	$0.99	Apr. 6, 2015
Android applications
Hypertension eDiary	Achtgrad AG	BP	Manual	Free	Oct. 15, 2015
Blood Pressure Diary	Cufit, Inc.	BP, weight	Syncs with bluetooth monitors	Free	Jan. 4, 2016
Blood Pressure Diary Pro	Fruct	BP	Manual	$2.19	Feb. 12, 2016
iBP Blood Pressure	Leading Edge Apps LLC	BP	Syncs with Withings Blood Pressure Monitor and Scalea	$0.99	Nov. 29, 2014
Blood Pressure (BP) Report Lite	TriStar Apps	BP	Manual	Free	Feb. 8, 2012
Blood Pressure Log	Dr. Tomasz Jan Zlamaniec	BP	Manual	Free	Nov. 22, 2015
Blood Pressure (BP) Watch	NumbersMatter2Me	BP, HR, weight	Manual	Free	Jul. 24, 2015
Blood Pressure Monitor Pro	KDSsuriyo	BP	Manual	Free	Jul. 6, 2015
Perf. Blood Pressure (BP) Monitor	Ufone Apps	BP	Measures pressure from thumb placed on screen	Free	Oct. 29, 2015
Blood Pressure	Freshware	BP, HR, medication, weight	Manual	Free	Jul. 30, 2014

^aFDA approved and validated

While there is insufficient evidence to recommend cuffless devices to patients at present, there are over 1000 clinical trials currently registered with www.clinicaltrials.gov to evaluate the feasibility, accuracy, and safety of various sensor technologies [16]. Collaborations between researchers and device innovators will be critical to moving such technologies forward prior to integrating them into clinical practice.

Smartphone Applications

Mobile or mHealth is heralded as a panacea for many major public health problems including poor blood pressure awareness and control. Enthusiasm is warranted as 2/3 of US adults now own smartphones that are equipped with cameras and light and motion sensors. By 2017, half of the 3.4 billion smartphone users worldwide will be using mobile health apps [17]. Currently, over 100,000 mobile health apps are available, many of which are marketed to the consumer to address hypertension control or medication adherence; although 42 % of these require some payment, many come at no additional cost. Most are developed for patients, but 15 % are primarily for health-care professionals and offer continuing medical education (CME) credit, remote monitoring, and the ability to perform telehealth management.

Current hypertension apps offer many consumer-facing uses including automated blood pressure logging by syncing to wireless blood pressure devices, medication adherence alerts, and communication with health-care providers. Some apps can assist the user in interpreting blood pressure values and will alert the patient to contact their physician when blood pressures are alarmingly high or low. Others provide detailed lifestyle management recommendations in concordance with clinical practice guidelines [18]. In a 2014, in a review of the top 100 applications related to blood pressure offered on Google Play and Apple iTunes, 72 % of apps had tracking functions, 22 % had tools to enhance medication adherence, 37 % contained general information on hypertension, and 8 % contained information on dietary lifestyle modifications such as the Dietary Approaches to Stop Hypertension (DASH) diet. However, nearly 1 in 7 also made claims that they could transform the smartphone into a medical device to measure blood pressure, though none had documentation of validation nor were any paired with a blood pressure cuff to obtain actual measurements [19••]. Not surprisingly, there are growing concerns that, if left unchecked, mHealth-based hypertension apps may be misleading to users providing false and potentially dangerous information.

Beyond this, results on the efficacy of mHealth for hypertension control are mixed with some data supporting an improvement in health with a decrease in health-care utilization [18, 20], while other studies show no benefit [9]. In a recent meta-analysis of over 3000 patients, mobile phone text reminders increased medication adherence from 50 to 68 % [21]. Computerized message management systems make this option scalable and inexpensive. However, few health systems are providing reimbursement for these services and outcomes such as cardiovascular disease prevention are uncertain. In a prospective, randomized-control trial of patients with hypertension using smartphone-enabled wireless blood pressure cuffs in combination with remote monitoring by nurses, there was no difference between intervention and control groups in health-care utilization indices including the frequency of emergency department visits, office visits, and inpatient stays. Both groups averaged approximately 150 blood pressure measurements over a 6-month period and had an overall decline in diastolic blood pressure, but there was no difference in systolic blood pressure and no difference between groups was seen [9]. The intervention group did report a significant improvement in health self-management as characterized by a decrease in the propensity to view health status as due to chance.

Research and Regulation of mHealth Innovations

While mHealth developers are spearheading much innovation, several promising initiatives are being lead by researchers. The National Institute of Health (NIH) has established national Big Data Centers of Excellence as part of a Big Data to Knowledge initiative. This allows for the funding of interdisciplinary groups to develop the necessary infrastructure, methods, software, and tools to advance human health with new technologies. Major areas of research include improving the reliability and accuracy of devices, exploring how to best utilize the vast amount of data collected, and improving safekeeping of physiological measurements and patient data.

Currently, any blood pressure device that is brought to market must pass a validation protocol [8]. Noninvasive blood pressure measurement systems fall under the 510(k) Food and Drug Administration (FDA) submission type and may not be marketed to consumers prior to FDA approval. Given the shear volume of new health applications and technologies, it is not feasible for the FDA to provide sufficient oversight. However, the FDA-released recommendations in February 2015 [22] for developers and distributors that stated its agency would enforce regulatory requirements over apps that are used to diagnose, treat, or prevent a medical condition.

Relevance to Emergency Care

Mobile technologies addressing hypertension diagnosis and management are particularly relevant to emergency department physicians. As reported by McNaughton et al., 23.6 % of all adult emergency department (ED) visits are hypertension-related [23], with almost 1 % carrying a primary diagnosis of hypertension. Clinical guidelines recommend discharge for ED patients who have elevated blood pressure without signs or symptoms of end organ damage, with referral to outpatient, primary care for follow-up, and further testing as needed [24]. Unfortunately, timely follow-up is not always feasible and a process that incorporates home blood pressure monitoring post-ED discharge using validated devices to track blood pressure readings in advance of a primary care visit may decrease the latency to a hypertension diagnosis or help primary care physicians better titrate medications. Many device innovators offer remote monitoring capabilities that sync with the physician office electronic health records. Patients with particularly difficult to control blood pressures may benefit most from these technologies. Even patients with poor medication adherence can be helped with mobile reminders to take their medication. While there are many potential applications for blood pressure sensors and hypertension-related mHealth technologies in the emergency department setting, to date, there is no research in this realm.

As such, mHealth apps and other devices become more ubiquitous in the consumer environment, emergency physicians are also likely to encounter patients who present to the ED solely based on concern for elevated blood pressure readings. While some of these patients may indeed be justified in their reasoning, many more may be prompted by erroneous values. Accordingly, emergency physicians should be prepared to provide reassurance based on knowledge of afore-mentioned measurement inaccuracies.

Additional technology that may be relevant to emergency care includes methods to measure patient compliance using ingestible tracers that are attached to daily medications. These FDA-approved devices provide a direct measure of medication adherence by transmitting time-stamped messages to a cloud-based server [25]. Currently, their cost is prohibitory, but in the foreseeable future, physicians may be able to establish whether a hypertensive patient who presents to the ED with elevated blood pressure has underlying noncompliance or truly refractory and potentially dangerous hypertension. Given recent data from SPRINT showing the benefit of lower blood pressure goals, this may be an issue of increasing importance in an era that espouses organizational accountability for hypertension control [26].

Recommendations for Adaptation of mHealth into Physician Workflow

Many new blood pressure devices, apps, and remote monitoring systems are available to patients and health-care systems that may improve hypertension control, medication compliance, and physician access to repeated blood pressure measurements. While mHealth interventions still require rigorous evaluation through clinical trials, patient acceptance and interest in mHealth are increasing. Subpopulations that may benefit the most from these technologies include those in resource-limited areas [27], with poor medication adherence, and those on multiple medication [28]. Physicians should encourage patients to use websites with independent physician reviews, such as iMedicalApps, and read the entire app descriptions before downloading apps for health maintenance. Some app descriptions may have a disclaimer “for entertainment purposes only.” Blood pressure devices that are validated are available on the dabl Educational Trust website and can be freely searched by patients. Home blood pressure monitors using upper arm cuffs and ambulatory blood pressure devices that are validated can be used to establish a diagnosis of hypertension and aid in drug titration and monitoring; however, pending further study, existing sensor-based and cuff-free devices should not be used in clinical practice.

Conclusions

Wireless blood pressure monitors and hypertension apps may improve blood pressure control and drug adherence in patients. Stakeholders including policy makers, physicians, device manufacturers, and patients must work together to ensure that data from new technologies is kept private and benefits patients. While technology continues to evolve, more research that examines long-term health outcomes, costs, and risks is necessary before cuff-less blood pressure monitors and other mHealth-based hypertension apps can be recommended in clinical practice.