Nearly one in five young American adults may have high blood pressure, much more than previously thought, according to a study that challenges the widely held view that the figure is under one in twenty; but even if it is actually somewhere in between, the researchers say young adults and their doctors should not assume high blood pressure only occurs in older people.

People with high blood pressure have a much higher risk of stroke and heart disease, the leading cause of death among adults in the United States. It is also a condition that often shows no signs or symptoms, and many otherwise healthy people who have it first find out when a health professional measures their blood pressure.

For the study, published this week in the journal Epidemiology, researchers from the University of North Carolina (UNC) at Chapel Hill and colleagues, analyzed data on more than 14,000 men and women between the ages of 24 and 32 who participated in the 2008 National Longitudinal Study of Adolescent Health (known as Add Health, funded mainly by the National Institutes of Health, with contributions from other agencies and foundations).

The results showed that 19% of the participants had high blood pressure or hypertension, and only about half of them had ever been told by a health professional that they had the condition.

Lead author Quynh Nguyen, an epidemiology doctoral student at UNC Gillings School of Global Public Health, told the press that:

“The findings are significant because they indicate that many young adults are at risk of developing heart disease, but are unaware that they have hypertension.”

The results also showed that young men (27%) were more likely to have high blood pressure than young women (11%), and young adults with a college education (17%) were less likely to have high blood pressure than those who did not have a high school degree (22%).

The researchers believe their findings are important because the data is drawn from the first nationally representative, field-based study of hypertension to focus on young adults. Other studies have not done this, focusing on older populations where high blood pressure is more common and only including smaller samples of young adults.

Co-author Dr Kathleen Mullan Harris, interim director of the UNC Carolina Population Center, and principal investigator on the Add Health study, said they were surprised to find such a high rate of hypertension among the Add Health participants.

Add Health defined high blood pressure as 140/90 millimeters of mercury (mmHg) or more.

This is the same definition used in another widely cited and reputable study, NHANES, the National Health and Nutrition Examination Survey, which for the same period (2007-2008) as Add Health, reported a much lower 4% rate of high blood pressure for a similar age group.

Harris said while there is a gap in the findings of the two studies, they have the same message:

“Young adults and the medical professionals they visit shouldn’t assume they’re not old enough to have high blood pressure. This is a condition that leads to chronic illness, premature death and costly medical treatment.”

She said the processes that trigger these problems start early in life but are preventable, and urged young adults to check for high blood pressure now and “head it off at the pass”.

The researchers considered a number of reasons for why the Add Health and NHANES estimates should be so different. For instance they looked at differences in the characteristics of the participants, how they were surveyed (at home versus being examined at a center), and the accuracy and reliability of the blood pressure measurements.

But they did not think any of these factors could explain such a large gap in the estimates of the two studies.

There was also another significant area of difference in the results of the Add Health and NHANES results.

The Add Health results found the number of young adults with high blood pressure was nearly twice as many as the number who reported being informed of their condition by a health professional (11%).

(Co-author Eric Whitsel, who headed the biology section of the study, and who is associate professor of medicine in UNC’s School of Medicine said this did not surprise them since measuring blood pressure will find it in otherwise healthy young adults who might not be aware of having it).

But in the NHANES study, the pattern was the other way around: the number of people found to have high blood pressure when they underwent the examination for the study (4%) was half that who reported having a history of hypertension (9%).

“Discordance in National Estimates of Hypertension Among Young Adults.”
Nguyen, Quynh C.; Tabor, Joyce W.; Entzel, Pamela P.; Lau, Yan; Suchindran, Chirayath; Hussey, Jon M.; Halpern, Carolyn T.; Harris, Kathleen Mullan; Whitsel, Eric A.
Epidemiology, published online 23 May 2011
DOI: 10.1097/EDE.0b013e31821c79d2

Additional source: UNC School of Public Health.

Written by: Catharine Paddock, PhD