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Isolated systolic hypertension in young and middle-age adults was associated with an increased risk of death from cardiovascular causes later in life, according to a study done over 3 decades.

Men in the study with systolic blood pressure (BP) levels of 140 mmHg or higher and diastolic BP below 90 had a 28% increased risk for death from coronary heart disease compared with men with normal BP (hazard ratio 1.28, 95% CI 1.04-1.58), reported , of Northwestern University Feinberg School of Medicine in Chicago.

In addition, women with isolated systolic hypertension (ISH) had a more than twofold greater death risk (HR 2.12, 95% CI 1.49-3.01) than women with optimal BP, they wrote in the .

The findings provide strong evidence that ISH is a clinically meaningful condition in young and middle-age adults and not just pseudo or 'white-coat' hypertension, Lloyd-Jones told MedPage Today.

"It is not well supported by science, but there has been a belief by many that elevated systolic and not diastolic blood pressure in younger adults is benign," he said. "Most previous research hasn't really examined hypertension by subtype. That's why we did this study."

Study Details

ISH is defined as a systolic BP of 140 mmHg or greater with a diastolic BP of less than 90 mmHg. It is common in the elderly, but relatively uncommon in younger and middle-age adults, the researchers wrote.

NHANES data suggest that the overall prevalence of ISH among adults in their 20s and 30s has more than doubled in recent decades, from 0.7% between 1988 and 1994 to 1.6% between 1999 and 2004, but there is still a great deal of uncertainly about the clinical consequences of ISH in younger adults.

While two large nationwide, nested, case-control cohort studies -- one from the U.S. and one from Sweden -- suggested a link between hypertension in early adulthood and elevated risk of death from cardiovascular causes, neither examined risk by hypertension subtype, Lloyd-Jones said.

Lloyd-Jones and colleagues analyzed data from the , which followed 15,868 men and 11,213 women for 3 decades. Recruitment occurred between 1967 and 1973, and the participants had a mean age of 34 at enrollment. Many surviving members of the cohort are in their mid-70s today, Lloyd-Jones said.

All were free or coronary heart disease and none were taking medication for hypertension at enrollment. BP status was classified as follows:

• Optimal-normal BP: systolic BP<130 mmHg and diastolic BP<85 mmHg)
• High-normal BP: 130 to 139/85 to 89 mmHg
• ISH: systolic BP ≥140 and diastolic BP <90 mmHg
• Isolated diastolic hypertension (IDH): systolic BP<140 and diastolic BP ≥90 mmHg
• Systolic-diastolic hypertension (SDH): systolic BP ≥140 and diastolic BP ≥90 mmHg

'Not an Innocuous Condition'

The percentage of study participants with optimal-normal BP was 26.9%, while 24.3% had high-normal BP, 25.3% had ISH, 3.7% had IDH, and 19.8% had SDH.

The prevalence of ISH was 25% among the men in the study and 13% among the women. Among participants with hypertension, approximately half had ISH.

During an average follow-up of 31 years (842,600 person-years) a total of 1,728 study participants died from cardiovascular causes, 1,168 participants died due to coronary heart disease, and 223 died due to stroke.

After adjusting for important variables associated with death from these causes, such as age, race, education, body mass index, smoking status, total cholesterol, and diabetes, Cox analysis showed that compared with participants with optimal BP, HRs for death from cardiovascular disease and coronary heart disease for men with ISH were 1.23 (95% CI 1.03-1.46) and 1.28 (95% CI 1.04-1.58), respectively.

Among women, the HRs were 1.55 (95% CI 1.18-2.05) and 2.12 (95% CI 1.49-3.01) respectively.

ISH was not associated with stroke risk in either sex, with HRs of 1.1 in men (95% CI 0.6-1.9) and 1.5 in women (95% CI 0.8-2.8).

Among both sexes the risk for death from cardiovascular disease and coronary heart disease in the high-normal and the ISH groups was significantly higher, and men, but not women, with IDH also had a greater risk for death, although this condition was rare among both sexes.

Based on their findings, the researchers concluded ISH in young and middle-age adults "is not an innocuous condition," but they added that the strategy for lowering future risk is not clear.

"We cannot definitively infer whether the excess [cardiovascular disease] risk from ISH in younger and middle-age adults warrants antihypertensive drug therapy or whether only lifestyle modification treatment is necessary," they wrote, adding that research is needed to identify which younger adults with ISH are at greatest risk.

The study had some limitations. Patients were recruited between 1967 and 1973, before the onset of the obesity epidemic, the authors pointed out. As a result, the data may not reflect the impact of that epidemic on BP and BP-related risks. Also, there may have been residual confounding from factors such as socioeconomic status and diet, and the patient population consisted mainly of non-Hispanic white participants.

In an accompanying editorial, , of SUNY Downstate Medical Center in New York City wrote that the findings add to the evidence suggesting that early management of hypertension in young adults can reduce future risk.

"It could unwisely be argued that absolute event rates in young people, even when increased by high BP, remain relatively low," he wrote. "In fact, the growing prevalence of hypertension, along with obesity, lipid disorder, and diabetes, in young people has become a major public health issue. Indeed, it is to be hoped that early management of hypertension in young adults might beneficially alter its natural history and reduce the incidence of cardiovascular events in later life."

From the American Heart Association:

• Heart Disease and Stroke Statistics—2015 Update
• JNC 7: Complete Report--Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure

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