RELATION BETWEEN NOCTURNAL DECLINE IN BLOOD-PRESSURE AND MORTALITY - THE OHASAMA STUDY

To investigate the relation between nocturnal decline in blood pressur e and mortality, we obtained ambulatory blood pressures in 1542 reside nts aged 40 years or over of a rural Japanese community. Subjects were followed-up for a mean of 5.1 years and were then subdivided into fou r groups according to the percent decline in nocturnal blood pressure: 1) extreme dippers: percent decline in nocturnal blood pressure great er than or equal to 20% of the daytime blood pressure; 2) dippers: dec line of greater than or equal to 10% but < 20%; 3) nondippers: decline of greater than or equal to 0% but < 10%; and 4) inverted dippers: no decline. The relationship between the decline in nocturnal blood pres sure and mortality was examined by the Cox proportional hazards regres sion model adjusted for age, sex, smoking status, previous history of cardiovascular disease, and the use of antihypertensive medication. Th e mortality risk was highest in inverted dippers, followed by nondippe rs. There was no difference in mortality between extreme dippers and d ippers. This relationship was observed for both treated and untreated subjects, was more pronounced for cardiovascular than for noncardiovas cular mortality, and did not change after the data were adjusted for 2 4-h, daytime, and nighttime blood pressure levels. (C) 1997 American J ournal of Hypertension, Ltd.