Out-of-office blood pressure (BP) measured by home BP monitoring (HBPM) or ambulatory BP monitoring (ABPM) was demonstrated to be superior to office BP for the prediction of cardiovascular events. The ABPM is superior to HBPM for detecting the all the BP-related risks throughout 24-hr, and the self-measured HBPM underestimates the risk of daytime stress hypertension and nocturnal hypertension. However, ABPM cannot always be provided in clinical practice, and home BP monitoring can be superior to ABPM as part of a home BP-guided antihypertension strategy in clinical practice. In clinical practice, we should use both ABPM and HBPM considering these device properties. We have developed the new ABPM device which is alternatively used as self-measure HBPM (Kario. Prog Cardiovasc Dis 2016, in press).
The importance of on-treatment HBPM for the cardiovascular prognosis of hypertensive individuals was recently revealed in the largest real-world prospective study held to date, the Home blood pressure measurement with Olmesartan Naive patients to Establish Standard Target blood pressure (HONEST) study. That study of more than 21 000 hypertensive patients used HBPM, and the results demonstrated that when morning home systolic BP was well-controlled during the 2-year follow-up at < 125 mmHg, there was no increase in cardiovascular events even among the patients whose office systolic BP was ≥150 mmHg, compared with those with office systolic BP < 130 mmHg and morning home systolic BP < 125 mmHg. On the other hand, even when the office systolic BP of the HONEST study's hypertensive patients was well controlled at < 130 mmHg, the hazard ratio of cardiovascular events was 2.5 in the masked uncontrolled hypertension patients with morning systolic BP ≥145 mmHg compared with the well-controlled patients with morning systolic BP < 125 mmHg (Kario, et al. Hypertension 2014;64:989–996). The threshold of on-treatment morning BP for a significant increase in cardiovascular events was revealed to be 144 mmHg, and approx. 125 mmHg was shown to be the minimum risk. There was no J-curve of morning systolic BP until around 100 mmHg. In a sub-analysis of the HONEST patient series with data separated for stroke and coronary events, the morning home BP values were a strong predictor of coronary events similarly to stroke events, but the predictive power of office systolic BP was weaker for coronary events than for stroke event (Kario, et al. J Am Coll Cardiol 2016;67:1519–1527). In addition, a J-curve was not observed in the relationship between morning home BP for coronary events or for stroke events.
Nocturnal BP has traditionally been measured only by ABPM, and the clinical evidence of nocturnal hypertension is established based on the ABPM data. However, nocturnal BP can now be measured by HBPM as an alternative to ABPM. In our nationwide Japanese cohort, the Japan Morning Surge Home Blood Pressure (J-HOP) Study, we measured nocturnal BP by HBPM (Kario. J Clin Hypertens 2015;17:340–348). Morning home BP was the predictor of stroke event (Hoshide, Kario, et al. Hypertension 2016;68:54–61), while uncontrolled nocturnal hypertension was significantly associated with cardiovascular events. Since Asians show greater morning BP surges (Hoshide, Kario, Parati et al. Hypertension 2016;68:54–61), it is particularly important for Asians to achieve ‘perfect 24-hr BP control,’ i.e., the 24-hr BP level, nocturnal BP dipping, and BP variability including morning surge (Kario. Ann Glob Health 2016;82:254–273). We are developing the new ICT-based BP monitoring such as “IT-based home nocturnal BP monitoring” (Kario. Hypertens Res 2013;36:478–484) and “hypoxia-triggered home nocturnal BP monitoring (TNP)” (Kuwabara, Kario, et al. J Clin Hypertens 2016, in press) to clarify the clinical relevance of 24-hour BP control.
A morning home BP-guided staged approach is the first step toward perfect 24-hr BP control, followed by the control of nocturnal hypertension (Kario. Essential manual of 24 hour blood pressure management. Wiley, UK, pp.1–158.2015). The ICT-based approach will contribute to achieve ideal home BP level and its seasonal variation (120 mmHg in summer and 125 mmHg in winter) (Nishizawa, Kario, et al. J Clin Hypertens 2016, in press).