Serial blood pressure measurements during young adulthood appear to predict the risk of subclinical coronary artery calcification, a surrogate for CVD risk, in middle age, according to a report published online Feb. 4 in JAMA.
In particular, even slightly elevated blood pressure at ages 18-30 years, if it persists or rises over time, is strongly associated with coronary artery calcification (CAC) 25 years later, said Norrina B. Allen, Ph.D., of the department of preventive medicine, Northwestern University, Chicago, and her associates.
© American Heart Association
Even slightly elevated blood pressure at ages 18-30 years, if it persists or rises over time, is strongly associated with coronary artery calcification 25 years later, said Dr. Allen.
The investigators tracked blood pressure patterns using data for 4,681 individuals in the CARDIA (Coronary Artery Risk Development in Young Adults) study, a longitudinal cohort study that involves racially diverse men and women, who, at baseline in 1985-1986, resided in four urban areas across the country as young adults and who were followed for 25 years. Subclinical coronary atherosclerosis was quantified using CAC at the 25-year assessment in 3,442 of these study subjects.
Although both systolic and diastolic blood pressure were assessed at intervals over the years, Dr. Allen and her colleagues focused on mid-BP, defined as the mean of systolic and diastolic measurements. Mid-BP is the best predictor of overall cardiovascular disease, compared with systolic BP alone, diastolic BP alone, pulse pressure, or mean arterial pressure, and its use permits researchers to study the effects of systolic and diastolic BP simultaneously.
These individuals showed five distinct trajectories in blood pressure:
• Group 1: low BP throughout the entire study period (22% of the entire study population).
• Group 2: moderate BP throughout the entire study period (42%).
• Group 3: moderate BP at baseline with a rapid increase in BP beginning at an average age of 35 (12%).
• Group 4: somewhat elevated BP throughout the study period (19%).
• Group 5: high blood pressure that continued to rise over time (5%).
Dr. Norrina Allen
Two of these groups showed the largest and most rapid increases in BP over time. Subjects in group 3 showed a mean increase of 30.2 mm Hg in systolic and a mean increase of 20.9 mm Hg in diastolic BP by middle age, and subjects in group 5 showed a mean increase of 21.2 mm Hg in systolic and 11.5 mm Hg diastolic BP.
The prevalence of CAC rose steadily in accordance with the BP trajectory, from a low of 4% in group 1 patients with a low-and-stable BP trajectory to a high of 25% in group 5 patients with a high-and-increasing BP trajectory. "Importantly, the majority of these participants had BP levels within the range of prehypertension," the investigators said.
After the data were adjusted to account for numerous potentially confounding factors, the odds ratios for developing CAC rose by 3%, 5%, 6%, and 13% for groups 2 through 5, respectively, compared with group 1, Dr. Allen and her associates said (JAMA 2014 Feb. 4 [doi:10.1001/jama.2013.285122]).
This pattern persisted when systolic and diastolic BP values were analyzed separately, and did not change in a sensitivity analysis restricted to the 3,507 participants who did not take any antihypertensive medication during follow-up.
"Our findings ... suggest that these trajectory groups provide important additional information regarding the presence of significant levels of subclinical atherosclerosis, which has been shown to be a strong indicator of future cardiovascular risk. This understanding of the effect of change or timing of change in BP on subclinical atherosclerosis may be important for risk stratification in the future," the investigators said.
Future research should address the usefulness of these trajectories in predicting clinical CVD events, as well as the effects of treatments and lifestyle modification on lifetime trajectories of BP, they added.
The CARDIA study was supported by the National Heart, Lung, and Blood Institute; University of Alabama at Birmingham; Northwestern University; University of Minnesota; Kaiser Foundation Research Institute; Johns Hopkins University; and the National Institute on Aging. Dr. Allen reported no financial conflicts of interest; an associate reported ties to Merck and Takeda.