Status of home blood pressure measured in morning and evening: Evaluation in normotensives and hypertensives in Japanese urban population

Abstract

To assess home blood pressure status in a Japanese urban population, we analyzed home blood pressure values in normotensive subjects determined by casual blood pressure (<140/90 mmHg), hypertensive subjects without medication (≥140/90 mmHg) and treated hypertensive patients. The subjects (468 male, 232 female; mean age 41 years old) were recruited from a company located in Tokyo. Home blood pressure was measured with a semi-automatic device (Omron HEM-759P). Subjects were instructed to perform triplicate morning and evening measurements on 7 consecutive days. In the treated hypertensive group (n=70), there was a significant difference between morning (139 ± 12/88 ± 9 mmHg) and evening (130 ± 12/79 ± 8 mmHg) home blood pressure. In the normotensive group (n=558), however, only the diastolic blood pressure (DBP) component of the home blood pressure was significantly different between morning (115 ± 13/72 ± 9 mmHg) and evening (114 ± 12/68 ± 8 mmHg). In the nontreated hypertensive group (n=72), casual blood pressure (145 ± 14/92 ± 9 mmHg) was higher than morning (138 ± 16/89 ± 11 mmHg) and evening (134 ± 16/83 ± 11 mmHg) home blood pressure, but no difference was seen between morning and evening systolic blood pressure (SBP). According to the reference value of the Japanese Society of Hypertension 2004 (SBP ≥ 135 mmHg and/or DBP ≥85 mmHg), 7.2% (systolic) and 8.7% (diastolic) of subjects in the normotensive group were classified as hypertensive by home blood pressure. Casual blood pressure in the treated hypertensive group was normal in 64.3% for SBP and 70.0% for DBP. However, their morning SBP (32.9%), morning DBP (40.0%), evening SBP (10.0%), and evening DBP (17.1%) were classified as hypertensive by home blood pressure. Furthermore, patients who were taking antihypertensive drug(s) only in the morning (n=52) showed higher morning SBP (6 mmHg, p=0.086) and morning DBP (6 mmHg, p=0.005) than patients taking drug(s) by other administration schedules (n=18), but no difference in evening home blood pressure was observed. In conclusion, a proportion of the subjects defined as normotensive by casual blood pressure were classified as hypertensive by home blood pressure in the present urban population. Furthermore, morning home blood pressure control in the treated hypertensive group classified as under control by casual blood pressure was insufficient, especially in patients who were taking medication only in the morning.