LET'S START WITH THE FACTS
It’s no secret among healthcare professionals that hypertension is a rampant problem across the worldwide population. If you’re a physician reading this, you know the facts; an estimated 1 in 4 adults have high blood pressure (BP) which equates to 1.13 billion worldwide [1]. As a condition that rarely causes symptoms, most hypertensives are living unaware of their condition and of the extreme damage it is wreaking on their health. High BP is known to be the most powerful and independent risk factor for cardiovascular disease and contributes to half of all strokes and heart attacks [2-4]. In 2015, cardiovascular diseases accounted for 10.7 million deaths worldwide [5]. It is also a known risk factor in kidney disease which can then lead to kidney failure, for which high BP is one of the top causes, second only to diabetes. In 2012, more than 1.8 million people in the UK alone had a diagnosis of kidney disease and another 1.0 million were suspected to be undiagnosed [6]. In addition to the human suffering, globally suboptimal BP control is estimated to cost $370 billion USD in healthcare spending each year [7].
It is safe to conclude, then, that this risk factor has reached epidemic proportions and, despite the fact that the knowledge necessary to prevent and control hypertension exists, control rates are dismal in every part of the world [8]. So, why is this?
To be fair to us (read: humanity), it’s tricky to effectively treat and monitor a condition that is by its very nature symptomless and therefore difficult to detect in the first place. As well as being symptomless, there are a range of other factors which have led this very preventable and controllable silent killer to run riot.
Challenges surrounding the diagnosis and monitoring of hypertension include the prevalence of ‘white coat’ and masked hypertension. White coat hypertension is a condition by which patients persistently have elevated BP in the presence of a healthcare professional but have normal out-of-office BP. This is associated with an increased risk of organ damage and cardiovascular morbidity and mortality [9], accounting for approximately 25-46% of all patients identified as having elevated blood pressure in the clinic [10]. Conversely, masked hypertension is characterised by normal in-office BP accompanied by elevated BP in out-of-office measurements [9]. Masked hypertension is also associated with a higher prevalence of organ damage as well as increased cardiovascular risk and all-cause mortality [11]. These two conditions can also be compounded by improper BP measuring techniques (e.g. incorrect patient positioning, left arm vs right arm discrepancies, use of an incorrectly sized blood pressure cuff for the patient’s arm, inadequate rest periods before measurements taken etc.) and are subject to operator bias, which muddies the waters of monitoring and diagnosis even further.
Treatment-related challenges also contribute to hypertension’s advance. Antihypertensive drug resistance affects the 10% of the hypertensive patient population who require ≥4 antihypertensive drugs of different classes to achieve BP control, and even after effective control is achieved, these patients are still associated with an increased risk of cardiovascular disease [12]. Poor medication adherence is also a huge issue, with as many as 50-80% of hypertensive patients demonstrating suboptimal adherence to their prescribed antihypertensive medications [13].
Once elevated BP readings are first detected at a clinic visit, patients have traditionally been sent home with either ambulatory blood pressure monitoring (ABPM) or home blood pressure monitoring (HBPM) kits to confirm the diagnosis by collecting readings over a longer period of time, thus providing physicians with more holistic insight into the patient’s condition to help inform interventions. However, the devices used in these kits can often be costly, hard to use accurately, and uncomfortable. They often interfere with a patient’s daily life and open up the opportunity for patients to report unreliable readings, leading to undiagnosed health risks or misinformed treatments such as over- and underuse of medications [14]. They also take up the invaluable and increasingly in-demand resource of the supervising practitioner’s time needed to fill the role of receiving, monitoring and managing the patient based on regular review of the BP readings.
This is not to say that home BP monitoring holds no value. Multiple studies have found evidence that, on the whole, home BP monitoring provides more accurate and reproducible measurements than in-office readings [15, 16]. It can also help in detecting white coat hypertension and may result in improved BP control [17 - 24]. Home monitoring can help patients see the effect lifestyle modifications and medication are having on their readings and make them more likely to adhere to treatment. Importantly, physicians have found that involvement in this form of home monitoring process improves patient care, and may reduce their need to intervene as much [25].
The true value, however, lies in the aforementioned ability to give physicians more insight into a patient’s BP over longer periods of time and make more rapid adjustments to medications to improve patient outcomes, and it is this benefit which has in recent years driven technological advancements into remote BP monitoring. Connected wearable devices taking the form of wristwatches, rings, stick-on patches, and more, are today offering a ‘cuffless’ BP solution to many of the problems cited in this article. Instead of hard-to-use, uncomfortable BP cuffs, patients wear a comfortable, Bluetooth-enabled device which at regular intervals uses advanced vitals monitoring technology to track BP-related biomarkers, store this data in a smartphone app and in turn transmit the data to a remote computer where diagnostic algorithms can analyse this data, detect abnormal readings and trigger an alert for the physician. Remote BP monitoring systems detect early deterioration and provide peace of mind as well as better access to care for patients. They can also track patient adherence to treatment and enable timely intervention reducing both healthcare utilisation and costs.
WHY IS HIGH BLOOD PRESSURE SUCH A HUGE PROBLEM?
HOW IS THE PROBLEM CURRENTLY BEING DEALT WITH?
SO, ARE CONNECTED WEARABLES THE ANSWER?
No, and here’s why
While connected wearables may have made significant progress towards optimising diagnosis, monitoring and treatment of hypertension, they are a fundamentally flawed solution to the blood pressure problem. Their primary limitations are threefold:
- These devices can be very costly and so rather than increasing hypertensives’ access to care as intended, they can perversely lower accessibility. This is an inherent contradiction present in any hardware-based medical device; patients need to acquire the device either individually or via prescription in order to access the health benefits. Most importantly, populations most at risk with cardiovascular disorder may be excluded by this cost.
- The connected devices can also alienate patient populations who tend to be more tech-averse, such as the elderly who have not grown up with technological changes.
- The time healthcare professionals need to dedicate to education and set-up to ensure accurate readings is very resource intensive.
So, what's the alternative?
An aspect of the hypertension epidemic that we have not highlighted yet is that projections estimate three-quarters of the world’s hypertensive population will reside in low- and middle-income countries (LMICs) within the next 5 years [26]. This concerning statistic once again stresses the importance that this is a global problem, and it requires a global solution, namely, a democratised solution that is exponentially scalable.
The solution is likely staring you in the face as you’re reading this, or in your pocket; your smartphone. It is estimated that 48.46% of the world’s population owns a smartphone; for example 71.34% of Europe, 30% of North Africa, 76.5% of Northern America, 40.8% of the Middle East, 59.9% of China and 25.3% of India’s populations own smartphones [27]. By harnessing the power of the ubiquitous smartphone, we can remove the need for any hardware component in remote BP monitoring. This then truly democratises the ability to detect undiagnosed hypertension cases, facilitate more proactive intervention and empower hypertensives to feel more in control of their own health and therefore to more effectively manage their conditions.
How can we do this?
Anyone can download the Blueprint (formerly FoneDx) app our team has developed and with no education or set-up needed follow the familiar app user experience to position the phone in the palm of your hand for a few seconds. Machine learning algorithms then analyse the resulting hemodynamic signature to determine BP, alongside other vital signs.
In a bid to not only crack the blood pressure problem but also to revolutionise healthcare delivery globally, we are placing the key to unlock increased access to care and improved patient outcomes into the pockets of 6 billion people [28].
REFERENCES
[1] WHO. Fact sheet on Hypertension [Internet]. 2019. Available from: https://www.who.int/news-room/fact-sheets/detail/hypertension.
[2] al-Roomi KA, Heller RF, Wlodarczyk J. Hypertension control and the risk of myocardial infarction and stroke: a population-based study. Med. J. Aust. 1990;153:595-599,602-603.
[3] Borghi C, Bacchelli S, Esposti DD, et al. Effects of the administration of an angiotensin-converting enzyme inhibitor during the acute phase of myocardial infarction in patients with arterial hypertension. SMILE Study Investigators. Survival of Myocardial Infarction Long-term Evaluation. Am. J. Hypertens. 1999;12:665–672.
[4] Marmot MG, Poulter NR. Primary prevention of stroke. Lancet (London, England). 1992;339:344–347.
[5] Mensah, George A. Epidemiology and global burden of hypertension. Oxford University Press. (Oxford, 2018).
[6] National Health Service. Chronic Kidney Disease in England: The Human and Financial Cost. 2012; Available from: https://www.england.nhs.uk/improvement-hub/wp-content/uploads/sites/44/2017/11/Chronic-Kidney-Disease-in-England-The-Human-and-Financial-Cost.pdf.
[7] Gaziano, Thomas A; Bitton, A; Anand, Shuchic; Weinstein, Milton for the International Society of Hypertension The global cost of nonoptimal blood pressure, Journal of Hypertension: July 2009 - Volume 27 - Issue 7 - p 1472-1477. doi: 10.1097/HJH.0b013e32832a9ba3
[8] Chockalingam A, Campbell NR & Fodor JG. Worldwide epidemic of hypertension. Can J Cardiol. 2006;22(7):553-555. doi:10.1016/s0828-282x(06)70275-6
[9] Kario K, Thjis L, Staessan J. Blood Pressure Measurement and Treatment Decisions. Circulation Research. American Heart Association. 2019;124:990–1008. https://doi.org/10.1161/CIRCRESAHA.118.313219
[10] Mancia G, Bombelli M, Brambilla G, et al. Long-term prognostic value of white coat hypertension: an insight from diagnostic use of both ambulatory and home blood pressure measurements. Hypertension. 2013;62(1):168-174. doi:10.1161/HYPERTENSIONAHA.111.00690
[11] Mancia, G., Bombelli, M., Seravalle, G. et al. Diagnosis and management of patients with white-coat and masked hypertension. Nat Rev Cardiol 8, 686–693 (2011). https://doi.org/10.1038/nrcardio.2011.115
[12] Holmqvist L, Boström KB, Kahan T, et al. Cardiovascular outcome in treatment-resistant hypertension: results from the Swedish Primary Care Cardiovascular Database (SPCCD). J Hypertens. 2018;36(2):402-409. doi:10.1097/HJH.0000000000001561
[13] Quadery SR, Swift AJ, Billings CG, et al. The impact of patient choice on survival in chronic thromboembolic pulmonary hypertension. Eur Respir J. 2018;52(3):1800589. Published 2018 Sep 16. doi:10.1183/13993003.00589-2018
[14] Ringrose JS, Polley G, McLean D, et al. An Assessment of the Accuracy of Home Blood Pressure Monitors When Used in Device Owners. Am. J. Hypertens. 2017;30:683–689.
[15] Appel LJ, Stason WB. Ambulatory blood pressure monitoring and blood pressure self-measurement in the diagnosis and management of hypertension. Ann. Intern. Med. 1993;118:867–882.
[16] Jula A, Puukka P, Karanko H. Multiple clinic and home blood pressure measurements versus ambulatory blood pressure monitoring. Hypertens. (Dallas, Tex. 1979). 1999;34:261–266.
[17] Pickering TG. Home blood pressure monitoring: a new standard method for monitoring hypertension control in treated patients. Nat. Clin. Pract. Cardiovasc. Med. 2008;5:762–763.
[18] Bonafini S, Fava C. Home blood pressure measurements: advantages and disadvantages compared to office and ambulatory monitoring. Blood Press. 2015;24:325–332.
[19] Cuspidi C, Meani S, Fusi V, et al. Home blood pressure measurement and its relationship with blood pressure control in a large selected hypertensive population. J. Hum. Hypertens. 2004;18:725–731.
[20] Uhlig K, Patel K, Ip S, et al. Self-measured blood pressure monitoring in the management of hypertension: a systematic review and meta-analysis. Ann. Intern. Med. 2013;159:185–194.
[21] Cappuccio FP, Kerry SM, Forbes L, et al. Blood pressure control by home monitoring: meta-analysis of randomised trials. BMJ. 2004;329:145.
[22] Bray EP, Holder R, Mant J, et al. Does self-monitoring reduce blood pressure? Meta-analysis with meta-regression of randomized controlled trials. Ann. Med. 2010;42:371–386.
[23] Agarwal R, Bills JE, Hecht TJW, et al. Role of home blood pressure monitoring in overcoming therapeutic inertia and improving hypertension control: a systematic review and meta-analysis. Hypertens. (Dallas, Tex. 1979). 2011;57:29–38.
[24] Glynn LG, Murphy AW, Smith SM, et al. Interventions used to improve control of blood pressure in patients with hypertension. Cochrane database Syst. Rev. 2010;CD005182.
[25] Zullig LL, Melnyk SD, Goldstein K, Shaw RJ, Bosworth HB. The role of home blood pressure telemonitoring in managing hypertensive populations. Curr Hypertens Rep. 2013;15(4):346-355. doi:10.1007/s11906-013-0351-6
[26] Kearney PM, Whelton M, Reynolds K, Muntner P, Whelton PK, He J. Global burden of hypertension: analysis of worldwide data. Lancet. 2005;365(9455):217-223. doi:10.1016/S0140-6736(05)17741-1
[27] Newzoo, Global Mobile Market Report, 2021. Results available from Bankmycell.com, How Many Smartphones Are in the World?, 2021. Available from: https://www.bankmycell.com/blog/how-many-phones-are-in-the-world#sources
[28] Statista. Number of smartphone subscriptions worldwide 2016-2027. February 2022. Available from: https://www.statista.com/statistics/330695/number-of-smartphone-users-worldwide/ (Last accessed 19/04/2022)
