Lower Hypertension Range Tied to Heightened CVD Risk in Younger Adults

Defining stage 1 hypertension as starting at a blood pressure of 130/80 mm Hg, as is now recommended in the latest comprehensive US guideline, identifies young adults who are risk for cardiovascular events in the next few decades, two studies published in a hypertension-themed issue of JAMA suggest.

In an analysis of the CARDIA study, which enrolled black and white individuals ages 18 to 30 from four US metropolitan areas, people who developed stage 1 hypertension before age 40 had a significantly heightened risk of CVD over a median follow-up of 18.8 years compared with those who had normal BP (adjusted HR 1.75; 95% CI 1.22-2.53), researchers led by Yuichiro Yano, MD, PhD (Duke University, Durham, NC), report.

Similarly, another study of nearly 2.5 million Korean adults younger than 40 showed that having stage 1 hypertension based on the new classification was associated with a greater risk of CVD over a median follow-up of 10 years in both men (adjusted HR 1.25; 95% CI 1.21-1.28) and women (adjusted HR 1.27; 95% CI 1.21-1.34), Joung Sik Son, MD (Seoul National University Hospital, South Korea), and colleagues report.

In the new hypertension guideline released last year, the American College of Cardiology (ACC), the American Heart Association (AHA), and nine partnering organizations lowered the threshold for defining hypertension based on prior data showing that BP values in that range were associated with increased cardiovascular risks (a move not followed by the Europeans). But those previous studies mostly involved middle-age and older adults, with a relative lack of evidence in younger populations.

Seulggie Choi, MD (Seoul National University Graduate School), a co-author of the Korean study, said these data showing a link between stage 1 hypertension in adults younger than 40 and later CVD provides support for the new classification, but added that future studies examining risks of other potential complications of hypertension, such as heart failure or chronic kidney disease, are needed to further refine the best BP cutoff for diagnosis.

“While more studies are needed, it may be beneficial for these young adults with hypertension to have their blood pressure managed, particularly by lifestyle behavior change,” Choi told TCTMD. “It’s never too early to take care of your health . . . and young adults should be more aware of the potential risks of hypertension, even at this young age.”

‘Elevated’ BP Carries Risk, Too

Yano and colleagues looked at data from the CARDIA study, which recruited individuals living in Birmingham, AL, Chicago, IL, Minneapolis, MN, and Oakland, CA. The analysis included 4,851 people with a mean age of 36. Half of participants were African-American, and 55% were women.

Using BP readings before age 40, the researchers divided the cohort into four groups:

• Normal (untreated BP < 120/80 mm Hg): 53%
• Elevated (untreated systolic 120 to 129 mm Hg and diastolic < 80 mm Hg): 9%
• Stage 1 hypertension (untreated systolic 130 to 139 mm Hg or diastolic 80 to 89 mm Hg): 25%
• Stage 2 hypertension (systolic ≥ 140 mm Hg, diastolic 90 mm Hg or higher, or taking antihypertensives): 13%

During follow-up, CVD incidence rates (per 1,000 person-years) across increasing BP categories were 1.37, 2.74, 3.15, and 8.04. On multivariable adjustment, there were significantly increased CVD risks in those with elevated BP (adjusted HR 1.67; 95% CI 1.01-2.77), stage 1 hypertension (adjusted HR 1.75; 95% CI 1.22-2.53), and stage 2 hypertension (adjusted HR 3.49; 95% CI 2.42-5.05).

All-cause mortality risk also was elevated in those with stage 2 hypertension (adjusted HR 2.19; 95% CI 1.61-2.99).

Yano told TCTMD that these findings bolster the new BP classification scheme, at least for diagnosis. “The new blood pressure guideline could help identify young adults at higher risk for CVD events in the future,” he said, “but we have no definitive answer for whether physicians should prescribe medication for the young adult with stage 1 hypertension or elevated blood pressure, essentially a lower-risk group.”

Consistency in the Korean Cohort

Findings similar to those seen in the CARDIA analysis were obtained by Son, Choi, and colleagues, who examined data from the Korean National Health Insurance Service. The median age of the cohort was 31, and 31.7% of participants were women.

Based on the ACC/AHA definitions, 40% had normal BP, 11% elevated BP, 38% stage 1 hypertension, and 12% stage 2 hypertension.

In both men and women, stage 1 hypertension was associated with greater risks of CVD (adjusted HR 1.25 for men and 1.27 for women), coronary heart disease (adjusted HR 1.23 for men and 1.16 for women), and stroke (adjusted HR 1.30 for men and 1.37 for women) compared with normal BP. Elevated BP and stage 2 hypertension also correlated with risks of those outcomes, with weaker and stronger relationships, respectively.

The researchers explored the impact of antihypertensive therapy prescribed within the first 5 years of follow-up, finding that stage 1 hypertension was associated with a higher CVD risk in untreated—but not treated—men and women.

What Should Be Done in Young Hypertensives?

Both Yano and Choi acknowledged that the absolute CVD risks associated with high BP seen in these younger cohorts—albeit elevated—were small and less than what would be seen in older age groups. In the Korean analysis, the investigators calculated that stage 1 hypertension resulted in an additional 5.1 and 3.9 CVD events per 1,000 men and women, respectively.

Nevertheless, Son et al write, “the difference in absolute risk and the fact that sustained hypertension during longer durations is associated with higher risk of CVD indicate that early blood pressure management among young adults may lead to significant public health benefits by reducing CVD risk later in life.”

Yano and Choi pointed to the importance of nonpharmacological strategies—like weight loss, exercise, and healthy eating—for managing young patients with hypertension, saying that randomized trials are needed to define what role drug therapy might play.

Whatever the approach, starting early is paramount, Yano added.

“The risk of CVD events among the group with elevated blood pressure is slightly increased, but if we continue over the lifetime the cumulative burden to the vasculature, brain, and heart is substantial,” he said. “So that’s the reason early intervention is really key.”

In an accompanying editorial, Ramachandran Vasan, MD (Boston University School of Medicine, MA), notes that the finding of a relationship between high BP and premature CVD risk in young adults does not necessarily mean that intervening to lower BP will improve outcomes.

He highlights, too, some gaps in knowledge regarding high BP earlier in life, including the origins of elevated BP in children and “the impact of social determinants of health, acculturation, and allostatic load on blood pressure trajectories in youth.” There also needs to be more clarity, he says, about factors that can guide treatment decisions and optimal BP targets in young adults with non-normal BP.

“Bridging these critical knowledge gaps may help define how, when, and what measures could be implemented to maintain an optimal blood pressure profile from childhood through young adulthood and beyond,” Vasan concludes. “Answers to these questions will be a public health legacy to the current generation of children and young adults and to their future offspring.”