Diabetes: Prehypertension - Why Should We Worry?

The blood pressure category known as prehypertension is an important marker of cardiac risk, yet it has not received adequate attention from health care providers and patients.1 Prehypertension is defined as a systolic blood pressure between 120 mm Hg and 139 mm Hg and a diastolic blood pressure between 80 mm Hg and 90 mm Hg.2 The seventh report of the Joint National Committee on the Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC 7) identified prehypertension to increase provider awareness of blood pressures that approach abnormal levels.1 Intervention in the prehypertension stage can reduce the likelihood of progression to hypertension.

Background
Approximately 50 million U.S. residents have been diagnosed with hypertension, and this number will continue to rise as the baby boomers enter their 60s.3 The incidence of hypertension increases with age. The Framingham Heart Study found that approximately 90% of participants whose blood pressure was normal at age 55 were diagnosed with hypertension later in life.4 Observational studies in adults ages 40 to 80 show that the risk of cardiovascular disease increases progressively, even with blood pressure levels as low as 115/75 mm Hg.5 For every increase of 20/10 mm Hg in blood pressure, the incidence of coronary heart disease and stroke doubles.4

Blood pressures in the prehypertension range may be associated with adverse cardiac events.1 The Framingham Heart Study documented a relationship between prehypertension and the progression to hypertension. 5 In patients with high normal blood pressure, it also identified a significantly increased risk of cardiovascular disease independent of other risk factors.6 The National Health and Nutrition Examination Survey I (NHANES) also documented a relationship between prehypertension and an increased risk for cardiovascular disease.1

The Strong Heart Study of 2,629 patients found that prehypertension was more prevalent in patients with diabetes than patients who did not have diabetes.7 This supports NHANES data showing that more than 88% of prehypertensive patients have at least one cardiovascular risk factor.1 Baseline data from NHANES I and NHANES III evaluated the long-term consequences of prehypertension and showed that the identification and elimination of prehypertension would reduce hospital admissions by 3.4%, nursing home admissions by 6.5% and deaths by 9.1%.1 Even with at least one risk factor for cardiovascular disease, the time to cardiovascular event is delayed in patients with prehypertension compared with patients who have hypertension. 1

Prehypertensive adults are at greater risk for cardiovascular disease, hypertensive renal disease and adverse cardiac events.8 Identifying and treating patients with prehypertension can prevent or delay hypertension and its subsequent adverse health-related events.4