AMBULATORY BLOOD-PRESSURE MONITORING - HOW REPRODUCIBLE IS IT

We tested the reproducibility of ambulatory blood pressure monitoring (ABPM) by the use of agreement plots. Thirty-two normotensive voluntee rs underwent ABPM on four separate days (interval 28 days), on the sam e typical weekday. Sleeping time was restricted to the ABPM nighttime subperiod from 11:00 PM to 7:00 AM. Twenty-four-hour average values-bo th systolic and diastolic-daytime average values, and nighttime averag e values, as well as standard deviation (SD) values, were analyzed for differences (analysis of variance). Adaptation occurred from the firs t to the fourth ABPM, ie, average 24 h, daytime, and nighttime values were lower (-1 to -3 mm Hg) during the fourth recording than the first (P < .05 to P < .01). The agreement analysis showed a surprisingly hi gh agreement among the four data sets tie, differences from +/-2.54 to +/-5.92 mm Hg; 2 SD of the distribution). We concluded that reproduci bility of ABPM seems excellent, but adaptation may occur, even in norm otensive volunteers under research conditions. Caution must be paid be fore labeling a patient as hypertensive, because initial ABPM may yiel d higher values than later monitorings. (C) 1997 American Journal of H ypertension, Ltd.