Ambulatory and Home Blood Pressure Normality in the Elderly

To determine ambulatory blood pressure (BP) means and distributions in an elderly population, we studied a random sample of 800 subjects stratified by sex and representative of residents aged 65 to 74 years of the city of Monza. Participation was 50%. Measurements consisted of clinic BP (average of three measurements with mercury sphygmomanometry), home BP (average of morning and evening measurements with a semiautomatic device), and ambulatory BP (SpaceLabs 90207). Clinic BP was obtained before and after home and ambulatory BP measurements. In normotensive and untreated hypertensive subjects (n=248), clinic, home, and ambulatory BPs were significantly related (P<.001). The means of the clinic BPs obtained on consecutive days were very similar and markedly higher than 24-hour average BP (+25 mm Hg systolic and + 10 mm Hg diastolic, P<.001). Nighttime BP was markedly less than daytime BP (-14 and -13 mm Hg, P<.001), whereas home BP values occurred approximately midway between clinic and 24-hour average BP values. Only minor differences existed between data in men and women, and the differences in clinic, home, and ambulatory BP values occurred in both normotensive and untreated hypertensive subjects. All BPs were similar in the untreated and treated hypertensive groups. Thus, as previously reported in subjects younger than 65 years, in the elderly fraction of the population, 24-hour average BP is much lower than clinic BP. The upper limit of normality for 24-hour average BP (calculated as the value corresponding to 140/90 mm Hg clinic BP) is about 120 mm Hg systolic and 76 mm Hg diastolic. At variance with data from younger subjects, home BP in the elderly is higher than 24-hour average BP. However, similar to data from younger subjects, clinic, home, and ambulatory BPs are higher in treated hypertensive than normotensive elderly subjects, indicating that in hypertensive elderly subjects, antihypertensive treatment does not commonly achieve full BP control both inside and outside the clinic environment.