Epidemiology of hypertension based on ambulatory blood pressure monitoring and self-measurement of blood pressure at home

Measurements of ambulatory blood pressure (ABP) and of home blood pressure (HBP) as an adjunct to casual/ clinic BP (CBP) measurements are currently widely used for the diagnosis and treatment of hypertension. We have monitored a rural cohort of people from the population of Ohasama, Japan, with respect to their prognosis and have previously reported that ABP and HBP are superior to CBP for the prediction of cardiovascular mortality. We examined the prognostic significance of white-coat hypertension for mortality and found that the relative hazard for the overall mortality of patients with white-coat hypertension was significantly lower than that for true hypertension during 5-year observation period but observed that the development of sustained hypertension was more frequent in patients with white-coat hypertension than those with true normotension during 10-year observation period. Our results also confirmed that day-by-day variability as well as short-term blood pressure variability (as measured every 30 min) was independently associated with cardiovascular mortality. In addition, research has recently focused on isolated systolic hypertension and pulse pressure as independent risk factors for poor cardiovascular prognosis. The Ohasama study also clearly demonstrated that isolated systolic hypertension and increased pulse pressure, as assessed by HBP, were associated with an increase in the risk of cardiovascular mortality. Concerning diurnal blood pressure variation, the relative hazard for cardiovascular mortality increased in non-dippers and inverted dippers while that in extreme dipper did not. The Ohasama study also clearly demonstrated that nocturnal BP levels in hypertensive patients with extreme dipper were significantly higher than those in normotensive subjects. The Ohasama study showed that the level and variability of hypertension as assessed by ABP and HBP are independent predictors of cardiovascular morbidity and mortality. It also demonstrated an independent association between the prognosis of hypertension and each component of ABP and HBP, indicating the prognostic significance of these blood pressure measurements.