High blood pressure is largely asymptomatic, especially in the early stages, leading to its description as a ‘silent killer’ . The asymptomatic nature of hypertension in conjunction with its disease burden necessitates routine blood pressure screening. In the UK, NICE guidelines recommend blood pressure measurement at least yearly among normotensive adults  and currently hypertension is largely identified in this way by physicians routinely or opportunistically assessing blood pressure in a primary care clinic setting . However, it has been estimated that between a third and a half of hypertensive patients remain undiagnosed, indicating the need for better screening . Developments in non-physician-based blood pressure measurements utilising new technologies may provide an opportunity for increased detection of hypertension.
Self-screening allows patients to measure their own blood pressure outside of physician consultations, either in their own home or with public validated solid cuff automatic sphygmomanometers that require no training, just simple instructions for use . In Japan, the market penetration of home blood pressure monitoring is such that it is estimated that more than enough monitors have been sold for one per household. In the UK, at least 1:10 normotensive adults have measured their own blood pressure at some time in the past . A recent systematic review  identified three studies of self-screening, which utilised public blood pressure cuffs in a variety of settings including pharmacies and grocery stores (Hamilton 2003 , Houle 2013 , Nykamp 2016 ). The majority of these were conducted in North America, where out-of-office blood pressure self-screening stations in pharmacies and work places are estimated to be used more than one million times a day . Providing additional blood pressure self-monitoring equipment in physician waiting rooms has been proposed in the UK to increase blood pressure screening , and such monitors are available in around a third of practice in the UK . Whilst several studies to date show promising results for feasibility, patient autonomy, convenience, and increased detection of hypertension (Hamilton 2003 , Houle 2013  and Tompson 2017 ), a number of barriers are yet to be overcome before widespread community self-screening can be recommended. These include limited privacy, poor awareness of the availability of the facilities, and a lack of education regarding the asymptomatic nature of hypertension and the benefits of screening .
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Breaking away from traditional cuff-based measurement of blood pressure, the widespread accessibility of smartphones and mobile health applications also offer new potential for the ubiquitous monitoring of parameters such as blood pressure. Recently, for example, the Cardiogram® application on the Apple® watch has been evaluated for its utility at using deep learning algorithms to predict hypertension from inputs of heart rate and step count. Data were collected from 6115 app users for an average of 9 weeks and predicted hypertension moderately well . This particular ‘app’ can now utilise multiple other wearable devices such as Fitbit®, Garmin® and Android devices; however, further research into its diagnostic utility is required. Furthermore, in the UK at least, current market penetration of smartphones into elderly populations is not sufficient for these techniques to be widely available in this key age group, but they have definite potential to aid detection of hypertension in younger adults [Ofcom communications market 2018]. In addition, cognitive deficits and visual or hearing impairments, which are more prominent in the older population, can decrease the accessibility of smartphone applications. It seems likely that further advances in technology will increase the spread of such techniques, but the need for long-term treatment of hypertension means that a formal diagnosis of hypertension is likely to remain paramount.