The association between orthostatic hypotension and the six-year incidence of hypertension:
the Atherosclerosis Risk in Communities study
This study examined the association between orthostatic hypotension (OH) and the six-year incidence of hypertension and isolated systolic hypertension (ISH) in 6,951 normotensive men and women free of CHD who participated in the baseline examination of the Atherosclerosis Risk in Communities (ARIC) study. OH, measured at baseline, was defined as a decrease in SBP ≥ 20 mm Hg or a decrease in DBP ≥ 10 mm Hg after changing from the supine to the standing position. Hypertension (SBP ≥ 140 mm Hg or DBP ≥ 90 mm Hg or current use of antihypertensive medications) and ISH (SBP ≥ 140 mm Hg and DBP < 90 mm Hg) status were ascertained at the second follow-up examination, which occurred approximately six years later. In unadjusted analyses, OH was associated with an increased risk of both hypertension (Odds Ratio (OR)= 2.07, 95% confidence interval (CI) = 1.51, 2.84) and ISH (OR=2.28, 95% CI = 1.53, 3.41). These associations were modestly attenuated after controlling for age, race, gender, BMI, and carotid intima media thickness. Baseline seated SBP was a significant effect modifier of both the OH - hypertension and the OH - ISH associations. Specifically, associations of OH with each of the outcomes were strongest among those with the lowest levels of baseline seated SBP (e.g., seated SBP of 90 mm Hg: OR = 4.8 for hyperetnsion and OR = 9.4 for ISH) and did not persist among those with the highest levels of baseline seated SBP (e.g., seated SBP of 130 mm Hg: OR = 1.1 for hypertension and OR = 1.0 for ISH). We conclude that OH is a strong predictor of hypertension and ISH in persons with low normal blood pressure at baseline and that OH in combination with low normal blood pressure may be an early indicator of impaired blood pressure regulatory systems.