Is self monitoring of blood pressure in pregnancy safe and effective?BMJ 2014; 349 doi: https://doi.org/10.1136/bmj.g6616 (Published 18 November 2014) Cite this as: BMJ 2014;349:g6616
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According to the Global Burden of Disease Study 2010 hypertension is the most important preventable cause of morbidity and mortality globally, affecting over 1 billion people.1 In Europe the prevalence of hypertension appears to be around 30–45% of the general population, with a steep increase with ageing.2 Furthermore, as a recent multinational study has shown, significant proportions of people are either unaware or have poor control of their elevated blood pressure (BP).3 Although the conventional office blood pressure (CBP) has been the cornerstone for hypertension diagnosis and management for decades, it is now recognized that, for the reliable evaluation of elevated BP, evaluation using 24-hour ambulatory (ABPM) or self-home BP monitoring (HBPM) is often required.2,4 Much evidence has accumulated that shows that HBP can predict hypertensive target-organ damage more effectively than CBP.5,6 Furthermore, several outcome studies demonstrated the prognostic value of HBPM for cardiovascular disease to be superior to that of CBP.6-8 HBP also seems to substantially refine risk stratification at CBP levels assumed to carry no or only mildly increased risk, in particular in the presence of masked hypertension.9
1. Diagnosis of hypertension
According to the ESH/ESC guidelines CBP currently remains the ‘gold standard’ for screening, and diagnosis of hypertension.2 However, out-of-office BP (HBPM and ABPM) is an important adjunct to conventional office BP measurement, especially when there is suspicion of white-coat, and masked hypertension.2 Several cross-sectional studies investigated the diagnostic performance of HBPM by taking ABPM as the reference method.10,11 There is considerable agreement between the two methods, with high specificity and negative predictive value (>80%) and lower sensitivity and positive predictive value (60–70%).11 This accruing evidence led both European and United States guidelines to emphasize the importance of HBPM in the diagnosis of hypertension.2,12 In Japan, HBPM is actually the preferred method for the diagnosis (and treatment) of hypertension.13 Although HBPM might be appropriate for the initial diagnostic evaluation of most cases with elevated BP (in primary care), ABPM if available might be more suitable when an unbiased evaluation is required within 24 hours (in specialist care).2,11 Furthermore, ABPM has the advantage of assessing BP variability and dipping status.4 However, HBPM can provide data on the short-term variability of BP14 and is also an excellent way to detect long-term variations in BP, including seasonal variations.15 A recent systematic review showed that preliminary data indicate an important and independent role of day-by-day HBP variability in the pathogenesis of hypertension induced cardiovascular damage.16 Furthermore, nowadays there are HBPM devices which allow nocturnal monitoring and have good agreement with ABPM in detecting non-dippers.17 HBPM during sleep as well as morning and evening HBP over a long period might provide reliable information on the nocturnal dipping status.13
2. Treatment of hypertension and long-term follow-up
Self-monitoring of hypertension is now common, with more than a third and up to two thirds of patients using it.18-20 Guidelines in Europe,21 the United States,22 and Japan23 recommend that HBPM should be offered to all patients with elevated BP, whereas ABPM monitoring should be offered in selected cases. A systematic review of 72 randomized controlled trials (RCT) that evaluated the effectiveness of several interventions (self-monitoring, educational interventions directed to the patient, educational interventions directed to the health professional, health professional-led care, organizational interventions that aimed to improve the delivery of care, and appointment reminder systems) aiming to improve BP control showed HBPM to be the most effective method.24 Furthermore, treated hypertensive patients who perform HBPM might have better long-term adherence to pharmacotherapy.25 Recent systematic reviews of RCT investigating self-monitoring have shown promise in the reduction of BP and higher hypertension control rates particularly when combined with other interventions, like tele-monitoring.26-29
3. Limitations of home blood pressure monitoring
The ESH Working Group on Blood Pressure Monitoring has proposed a number of recommendations for HBPM.21,30 It is imperative to follow these recommendations (avoid devices worn on the wrist; using accurate, independently validated devices; using 3–7 days with duplicate morning and evening measurements and discard the first day; objective reporting using automated memory or PC link; telemonitoring) in order for the HBPM to be trustworthy and meaningful.30 Only then can one avoid what is the biggest limitation of HBPM; the fact that hypertensive patients often misreport their HBPM values, which may affect treatment decisions made by physicians on such measurements.31 Furthermore, some patients may make self-adjustment of drug treatment.10 In some cases self-measured HBPM may not be possible because of cognitive impairment or physical limitations, or may be contra-indicated because of anxiety or obsessive patient behavior, in which case ABPM may be more suitable.2
With a growing global burden of hypertension and a growing availability of affordable and accurate BP measuring devices, HBPM could be used to diagnose high BP and help decide whom to treat.32 Furthermore, with smartphone applications that accept automated data uploads from HBPM devices and display BP trends over time, HBPM could be an excellent tool to follow-up treatment and BP control, and help save time for the physicians as they conduct remote consultations exploiting electronic tools for communication.32 When an unbiased assessment of BP is obtained according to the current ESH/ESC and international guidelines, HBPM can have a primary role in the diagnosis, treatment, and long-term follow-up of the majority of our hypertensive patients, especially given the fact that they can be really cost-effective.33
1. Lim SS, Vos T, Flaxman AD, et al. A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. Dec 15 2012;380(9859):2224-2260.
2. Mancia G, Fagard R, Narkiewicz K, et al. 2013 ESH/ESC guidelines for the management of arterial hypertension: the Task Force for the Management of Arterial Hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC). Eur Heart J. Jul 2013;34(28):2159-2219.
3. Chow CK, Teo KK, Rangarajan S, et al. Prevalence, awareness, treatment, and control of hypertension in rural and urban communities in high-, middle-, and low-income countries. JAMA. Sep 4 2013;310(9):959-968.
4. O'Brien E, Parati G, Stergiou G, et al. European Society of Hypertension position paper on ambulatory blood pressure monitoring. J Hypertens. Sep 2013;31(9):1731-1768.
5. Bliziotis IA, Destounis A, Stergiou GS. Home versus ambulatory and office blood pressure in predicting target organ damage in hypertension: a systematic review and meta-analysis. J Hypertens. Jul 2012;30(7):1289-1299.
6. Fuchs SC, Mello RG, Fuchs FC. Home blood pressure monitoring is better predictor of cardiovascular disease and target organ damage than office blood pressure: a systematic review and meta-analysis. Curr Cardiol Rep. Nov 2013;15(11):413.
7. Ward AM, Takahashi O, Stevens R, Heneghan C. Home measurement of blood pressure and cardiovascular disease: systematic review and meta-analysis of prospective studies. J Hypertens. Mar 2012;30(3):449-456.
8. Stergiou GS, Asayama K, Thijs L, et al. Prognosis of white-coat and masked hypertension: International Database of HOme blood pressure in relation to Cardiovascular Outcome. Hypertension. Apr 2014;63(4):675-682.
9. Asayama K, Thijs L, Brguljan-Hitij J, et al. Risk stratification by self-measured home blood pressure across categories of conventional blood pressure: a participant-level meta-analysis. PLoS Med. Jan 2014;11(1):e1001591.
10. Stergiou GS, Bliziotis IA. Home blood pressure monitoring in the diagnosis and treatment of hypertension: a systematic review. Am J Hypertens. Feb 2011;24(2):123-134.
11. Stergiou GS, Kollias A, Zeniodi M, Karpettas N, Ntineri A. Home blood pressure monitoring: primary role in hypertension management. Curr Hypertens Rep. Aug 2014;16(8):462.
12. Weber MA, Schiffrin EL, White WB, et al. Clinical practice guidelines for the management of hypertension in the community a statement by the American Society of Hypertension and the International Society of Hypertension. J Hypertens. Jan 2014;32(1):3-15.
13. Imai Y, Obara T, Asamaya K, Ohkubo T. The reason why home blood pressure measurements are preferred over clinic or ambulatory blood pressure in Japan. Hypertens Res. Aug 2013;36(8):661-672.
14. Johansson JK, Niiranen TJ, Puukka PJ, Jula AM. Prognostic value of the variability in home-measured blood pressure and heart rate: the Finn-Home Study. Hypertension. Feb 2012;59(2):212-218.
15. Imai Y, Munakata M, Tsuji I, et al. Seasonal variation in blood pressure in normotensive women studied by home measurements. Clin Sci (Lond). Jan 1996;90(1):55-60.
16. Stergiou GS, Ntineri A, Kollias A, Ohkubo T, Imai Y, Parati G. Blood pressure variability assessed by home measurements: a systematic review. Hypertens Res. Jun 2014;37(6):565-572.
17. Stergiou GS, Nasothimiou EG, Destounis A, Poulidakis E, Evagelou I, Tzamouranis D. Assessment of the diurnal blood pressure profile and detection of non-dippers based on home or ambulatory monitoring. Am J Hypertens. Sep 2012;25(9):974-978.
18. Baral-Grant S, Haque MS, Nouwen A, Greenfield SM, McManus RJ. Self-Monitoring of Blood Pressure in Hypertension: A UK Primary Care Survey. International Journal of Hypertension. 2012;2012:4.
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21. Parati G, Stergiou GS, Asmar R, et al. European Society of Hypertension practice guidelines for home blood pressure monitoring. J Hum Hypertens. Dec 2010;24(12):779-785.
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24. Glynn LG, Murphy AW, Smith SM, Schroeder K, Fahey T. Self-monitoring and other non-pharmacological interventions to improve the management of hypertension in primary care: a systematic review. British Journal of General Practice. December 1, 2010 2010;60(581):e476-e488.
25. Ogedegbe G, Schoenthaler A. A systematic review of the effects of home blood pressure monitoring on medication adherence. J Clin Hypertens (Greenwich). Mar 2006;8(3):174-180.
26. Bray EP, Holder R, Mant J, McManus RJ. Does self-monitoring reduce blood pressure? Meta-analysis with meta-regression of randomized controlled trials. Annals of Medicine. 2010;42(5):371-386.
27. Uhlig K, Patel K, Ip S, Kitsios GD, Balk EM. Self-measured blood pressure monitoring in the management of hypertension: a systematic review and meta-analysis. Ann Intern Med. Aug 6 2013;159(3):185-194.
28. Agarwal R, Bills JE, Hecht TJ, Light RP. Role of home blood pressure monitoring in overcoming therapeutic inertia and improving hypertension control: a systematic review and meta-analysis. Hypertension. Jan 2011;57(1):29-38.
29. Omboni S, Gazzola T, Carabelli G, Parati G. Clinical usefulness and cost effectiveness of home blood pressure telemonitoring: meta-analysis of randomized controlled studies. J Hypertens. Mar 2013;31(3):455-467; discussion 467-458.
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Competing interests: No competing interests
This article neatly summaries the issues with self monitoring physiological parameters. The pros and cons of this approach could apply to almost any chronic disease.
In respiratory medicine we have seen a new phenomenon of patients (and their carers) buying small portable pulse oximeters. These are available online for less than £20. It is now not unusual for paramedics to be called to a patient's house because self recorded oxygen saturations are low, frequently leading to a hospital admission.
This approach has several problems (as listed in the article) but more pertinently for patients with chronic respiratory disease there are very few treatments that can be started in response to an intermittently low oxygen saturation that patients are not already receiving. This can lead to frustration on behalf of both physician and patient.
Simple advice (based on much needed research) may help address this issue which, given the prevalence of COPD/asthma etc, allied to the falling cost of technology, will become more frequent.
Competing interests: No competing interests
Patient education for self care practices is of paramount importance in the management of chronic diseases such as hypertension, diabetes mellitus, coronary heart diseases, cerebrovascular diseases such as stroke, etc. The availability of self monitoring instruments for blood pressure digitally provides all the more support for promoting self care measurement. But such an approach needs careful patient education about the method of taking blood pressure, starting from the choice of cuff, placing the cuff, position of taking blood pressure, taking reading, precautions before taking blood pressure – not immediately after tea of coffee or foods or exercise, etc. The problem of choosing an appropriate, accurate and validated instrument should be taught to patients. A more important finding that should be emphasized is about fluctuations in blood pressure reading even by slight movements of hands/arms, anxiety, talking during taking blood pressure, etc. The role of relaxation before taking blood pressure should also be emphasized.
It has been generally observed that the first reading is always on the higher side even if the measurement is taken by oneself. In such circumstances, the measurements should be taken for at least three times, at intervals of 10 minutes and the lower reading should be taken. Opinions may vary, but there are no clarifications on this aspect about how many blood pressure readings should be taken. Some physicians advocate taking blood pressure readings twice a day, one in the morning and another in the evening, and keeping a record.
The idea of self monitoring of blood pressure is to help the patient understand about the stability of blood pressure for those on medications and help him/her monitor it so that in case of high blood pressure even after medication, it can be brought to the notice of the doctor for further management. The agreed level, i.e. 140/90 mm Hg, should preferably be taken as the limit since many cut off points may unnecessarily create a sense of anxiety and tension on the part of the patients. It is always better to get a lower reading than 140/90, but the criteria should not be changed until it is scientifically established.
Competing interests: No competing interests