DISCREPANCY BETWEEN SCREENING BLOOD-PRESSURE AND AMBULATORY BLOOD-PRESSURE - A COMMUNITY-BASED STUDY IN OHASAMA

We investigated factors underlying discrepancy between screening blood pressure and daytime ambulatory blood pressure(the difference) in a c ommunity-based population in northeastern Japan. Screening and ambulat ory pressures were measured in 706 untreated subjects aged 20 yr or ol der. We analyzed the effects of age and blood pressure on the differen ce and then performed multivariate stepwise linear regression analysis using the difference as the dependent variable. The systolic differen ce positively correlated with age in men. Women in their 40s exhibited a large difference, disturbing the linear relationship between the di fference and age. The difference positively correlated with the screen ing pressure in men and women. A positive difference (screening pressu re > ambulatory pressure) was observed at screening pressures above 13 0/75 mmHg. The difference inversely correlated with the ambulatory pre ssure. Multivariate analysis demonstrated that body mass index and mal e sex were positively associated with the systolic and diastolic blood pressure differences. The daytime pulse rate was negatively associate d with the systolic difference, and the standard deviation of daytime diastolic ambulatory blood pressure was positively associated with the diastolic difference. The diastolic difference in subjects with isola ted systolic hypertension based on the screening pressure was signific antly smaller than that in subjects with systolic/diastolic hypertensi on. The difference in subjects with isolated systolic hypertension bas ed on ambulatory pressure was significantly higher than that in systol ic/diastolic hypertension. When white-coat (isolated screening) hypert ension was defined as a screening systolic pressure greater than or eq ual to 140 mmHg, a diastolic pressure greater than or equal to 90 mmHg , or both, and a 24-h ambulatory pressure <136/87 mmHg in men and <131 /86 mmHg in women, white-coat (isolated screening) hypertension was pr esent in 79 (56.8%) of 139 subjects with screening hypertension. The r esults confirm that the discrepancy between screening and ambulatory b lood pressure is due to a variety of factors, including age, sex, bloo d pressure levels, and baroreflex function. Our results indicate that screening blood pressure in elderly hypertensive patients should be ev aluated carefully.