Population Study of Ambulatory Blood Pressure in a Rural Community in Northern Japan

A cross sectional survey was performed on ambulatory blood pressure (ABP) in a rural community in northern Japan. ABP was measured in 468 participants (148 men and 320 women, or 27.3% of the ≥20 year-old population in the study region) with a Colin ABPM 630, an ABP monitoring system. ABP was determined every 30 min for 24 hr. All-day average of 24 hr ambulatory systolic, (SBP) and diastolic BP (DBP) in these subjects were 121.5 ± 11.8 and 71.7 ± 8.0 mmHg (mean±S.D.), respectively. Ambulatory SBP and DBP levels increased gradually with an increase in age in both sexes. The age dependent increase in SBP was, however, extremely small in men compared with that in the casual SBP of the ordinary Japanese reported. The minimal age-dependent increase in ambulatory SBP in men reflects a high ambulatory SBP in those below 50 years-old as well as a minimal increase in ambulatory SBP in those over 50. Ambulatory SBPs in women were lower than those in men until they reach the age of 50 years. Ambulatory SBP levels in men and women were similar after their 60’s. Ambulatory DBP tended to fall or remain at the same level after 60 years-old. Thus, a greater pulse pressure was observed in elderly subjects. Casual SBP and DBP in the ordinary Japanese were significantly higher than the daytime average ambulatory SBP and DBP in all age groups of both sexes in the population except those in their 20’s. The result suggests that ABP has different clinical characteristics and may have a different clinical significance from casual BP.