Impressive evidence has accumulated to warrant greater attention to the importance of SBP as a major risk factor for CVDs. Changing patterns of BP occur with increasing age. The rise in SBP continues throughout life in contrast to DBP, which rises until approximately age 50, tends to level off over the next decade, and may remain the same or fall later in life (figure 13).^1,15 Diastolic hypertension predominates before age 50, either alone or in combination with SBP elevation. The prevalence of systolic hypertension increases with age, and above 50 years of age, systolic hypertension represents the most common form of hypertension. DBP is a more potent cardiovascular risk factor than SBP until age 50; thereafter, SBP is more important (figure 14).²² Clinical trials have demonstrated that control of isolated systolic hypertension reduces total mortality, cardiovascular mortality, stroke, and HF events.^23–25 Both observational studies and clinical trial data suggest that poor SBP control is largely responsible for the unacceptably low rates of overall BP control.^26,27 In the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) and the Controlled Onset Verapamil Investigation of Cardiovascular End Points (CONVINCE) Trial, DBP control rates exceeded 90 percent, but SBP control rates were considerably less (60–70 percent).^28,29 Poor SBP control is at least in part related to physician attitudes. A survey of primary care physicians indicated that three-fourths of them failed to initiate antihypertensive therapy in older individuals with SBP of 140–159 mmHg, and most primary care physicians did not pursue control to <140 mmHg.^30,31 Most physicians have been taught that the diastolic pressure is more important than SBP and thus treat accordingly. Greater emphasis must clearly be placed on managing systolic hypertension. Otherwise, as the United States population becomes older, the toll of uncontrolled SBP will cause increased rates of CVDs and renal diseases.

Figure 13

Changes in systolic and diastolic blood pressure with age SBP and DPB by age and race ;or ethnicity for men and women over 18 years of age in the U.S. population. Data from NHAES III, 1998–1991

Figure 14

Difference in coronary heart disease prediction between systolic and diastolic blood pressure as a function of age DBP, diastolic blood pressure; SBP, systolic blood pressure