Effect of aging on the prognostic significance of ambulatory systolic, diastolic, and pulse pressure in essential hypertension

Background-This study compared the relative prognostic significance of 24 h our intra-arterial ambulatory systolic blood pressure (SBP), diastolic bloo d pressure (DBP), mean arterial pressure (MAP), and pulse pressure (PP) par ameters in middle-aged versus elderly hypertensives. Methods and Results-A total of 546 subjects aged < 60 years and 142 subject s aged greater than or equal to 60 years who had undergone baseline pretrea tment 24-hour intra-arterial ambulatory blood pressure monitoring were foll owed for 9.2 +/- 4.1 years. Multivariate analysis showed that in younger su bjects, 24-hour, daytime, and nighttime DBP, MAP, and SBP, when considered individually, were positively related to morbid events; DBP parameters prov ided the best predictive values. In the group greater than or equal to 60 y ears (elderly group), 24-hour, daytime, and nighttime PP and SBP were the m ost predictive parameters, whereas ambulatory DBP and MAP measurements fail ed to provide any prognostic value. When 24-hour values of SBP and DBP were jointly included in the baseline model, DBP (z=2.02, P=0.04) but not SBP ( z= -0.43, P=0.67) was related to outcome in younger subjects, whereas in th e elderly group, SBP (z=3.33, P=0.001) was positively and DBP (z= - 1.75, P =0.07) was negatively related to outcome. Clinic blood pressure measurement s failed to provide any independent prognostic value in either age group. Conclusions-The relative prognostic significance of ambulatory blood pressu re components depends on age; DBP parameters provided the best prognostic v alue in middle-aged individuals, whereas PP parameters were the most predic tive in the elderly. This may reflect differing underlying hemodynamic mech anisms of hypertension in these age groups.