THE AMBULATORY BLOOD-PRESSURE IN NORMOTENSIVE AND HYPERTENSIVE SUBJECTS - RESULTS FROM AN INTERNATIONAL DATABASE

Objective: To delineate more precisely an operational threshold for ma king clinical decisions based on ambulatory blood pressure (ABP) measu rement by studying the ABP in subjects who were diagnosed as either no rmotensive or hypertensive by conventional blood pressure (CBP) measur ement. Subjects: Twenty-four research groups recruited 7069 subjects. Of these. 4577 were normotensive (systolic CBP less than or equal to 1 40 mmHg and diastolic CBP less than or equal to 90 mmHg) and 1773 were hypertensive (systolic CBP greater than or equal to 160 mmHg and/or d iastolic CBP greater than or equal to 90 mmHg). Of the latter, 1324 ha d systolic and 1310 had diastolic hypertension.Results: Ninety-five pe rcent of the normotensive subjects had a 24-h ABP below (systolic and diastolic, respectively) 133 and 82 mmHg. Of the patients with systoli c hypertension, 24% had a 24-h systolic ABP of <133 mmHg. Similarly, 3 0% of those with diastolic hypertension had a 24-h diastolic ABP of <8 2 mmHg. The probability that hypertensive patients had a 24-h ABP belo w these thresholds was higher in women than in men, increased with age and was 2- to 4-fold greater if the CBP of the patient had been measu red at only one visit and if fewer than 3 CBP measurements had been av eraged to establish the diagnosis of hypertension. By contrast, for ea ch 10-mmHg increment in systolic CBP, this probability decreased by 54 % for the 24-h systolic ABP and by 25% for the 24-h diastolic ABP, and for each 5 mmHg increment in diastolic CBP it increased by 6 and 9%, respectively. Conclusion: The ABP distributions of the normotensive su bjects included in the present international database were not materia lly different from those in previous reports in the literature. One-fi fth to more than one-third of the hypertensive patients had an ABP whi ch was below the 95th centile of the ABP in normotensive subjects, but this proportion decreased if the hypertensive patients had shown a hi gher CBP upon repeated measurement. The prognostic implications of ele vated CBP in the presence of normal ABP remain to be determined.