LIMITED REPRODUCIBILITY OF CIRCADIAN VARIATION IN BLOOD-PRESSURE DIPPERS AND NONDIPPERS

The relation between blood pressure (BP) variation and hypertensive or gan damage is controversial. The reproducibility of the circadian vari ation pattern acceptable as the standard for discriminating between '' dippers'' and ''nondippers'' has not yet been evaluated. We evaluated the reproducibility of ''dipper'' and ''nondipper'' patterns in essent ial hypertensives by monitoring BP for 48 h. Noninvasive ambulatory BP and heart rate (HR) monitoring for 48 h every 30 min were performed i n 253 untreated patients with mild-to-moderate essential hypertension. Mean daytime (awake) and nighttime (sleeping) systolic BP, diastolic BP, and HR values were analyzed by reviewing the patients' diaries. Pa tients were divided into two groups by presence (dippers) and absence (nondippers) of a reduction of both systolic and diastolic BP during t he night of > 10% of the daytime pressure. A subject who was a dipper on day 1 remained a dipper on day 2 in 41% (n = 103, DD group) and cha nged to nondipper in 16% (n= 41, DN group). A subject who was a nondip per on day 1 remained a nondipper on day 2 in 30% (n= 75, NN group) an d changed to a dipper in 13% (n = 34, ND group). Our findings indicate that there is a high risk of false-positive or false-negative results when 24-h recordings are used to identify dipper and nondipper profil es. (C) 1998 American Journal of Hypertension, Ltd.