Systolic blood pressure variability predicts stroke risk

Short-term, visit-to-visit variability in systolic blood pressure was associated with increased all-cause mortality, researchers reported.

Researchers used data from 956 patients in the third National Health and Nutrition Examination Survey. In that study, three consecutive blood pressure readings were taken during three separate study visits from 1988 to 1994. The first of the three was done at home. The second was recorded at a mobile exam center within one month, and the third was recorded between 1 and 48 days (median, 17) after the second.

Visit-to-visit blood pressure variability for each participant was defined using the standard deviation and coefficient of variation based on the mean of the second and third measurements from each visit. All-cause mortality was assessed through Dec. 31, 2006. The median follow-up was 14 years, during which time 240 (25.1%) of patients died. Results appeared online Jan. 3 in Hypertension.

The mean of the standard deviation for systolic blood pressure across visits was 7.7 mm Hg. After multivariable adjustment, older age, female gender, history of myocardial infarction, higher mean systolic blood pressure and pulse pressure, and use of angiotensin-converting enzyme (ACE) inhibitors were associated with higher standard deviation in systolic blood pressure.

After adjustment for age; sex; race/ethnicity; history of myocardial infarction; mean systolic blood pressure and pulse pressure; and ACE inhibitor, beta-blocker, calcium-channel blocker and thiazide-type diuretic use, the hazard ratio for all-cause mortality was 1.57 (95% CI, 1.07 to 2.18) and 1.50 (95% CI, 1.03 to 2.18) for the middle and highest versus lowest tertile of standard deviation of systolic blood pressure (P=0.064 for trend). The hazard ratio was 1.55 (95% CI, 1.09 to 2.22) and 1.49 (95% CI, 1.05 to 2.10) for the middle and highest versus lowest tertiles of coefficient of variation of systolic blood pressure (P=0.040 for trend).

An editorial in the same issue explained, "It should be emphasized that this intermediate BP variability may help the practicing physician to optimize antihypertensive treatment more than the long-term one because information can be collected quickly rather than after months or years, when the damage of inconsistent BP control has progressed and treatment modifications may come too late."