Study links pre-hypertension to serious risk

Meta-analysis shows bump in blood pressure ups chances of having a stroke by 55%

Hypertension or abnormally high blood pressure (an average reading of 140/90 mmHg or greater) is a well-known and much-documented health threat. It’s a major risk factor for heart disease and stroke, contributing to one in seven deaths in the United States, according to the Centers for Disease Control, including nearly half of deaths related to cardiovascular disease.

More than one-third of American adults have hypertension; another third have “pre-hypertension” or blood pressure that is elevated, but still within “normal” range: 120-139 mmHg systolic and 80-89 mmHg diastolic. In a new, published meta-analysis of general population studies that looked at the health impact of pre-hypertension, University of California San Diego neurologist and professor of neuroscience Dr. Bruce Ovbiagele and colleagues report that even “normal” but elevated blood pressure appears to significantly increase the risk of future stroke.

Q: How much more at risk of a stroke are people with pre-hypertension?

A: Overall, we found that people who had pre-hypertension were at 55 percent higher risk of a future stroke than people without pre-hypertension. This result held true regardless of sex, race-ethnicity, blood pressure type (systolic or diastolic) or stroke type (ischemic or hemorrhagic). The risk was even greater for those at the highest end of the pre-hypertension range. They were 79 percent at higher risk of a future stroke.

Q: The concept of pre-hypertension is relatively new and somewhat controversial. Why?

A: Pre-hypertension is a clinical category introduced by a committee of hypertension experts in 2003 to identify individuals who might be at future risk of developing hypertension and experiencing heart attacks, strokes, heart failure and kidney disease. It was based on expert opinion, not specific empirical data. There have been occasional accusations that the category would not be used to diagnose sick people, but rather it would label healthy people whose blood pressure was toward the upper reaches of normal as unhealthy, without any compelling reason for doing so. Some people complained that the new designation would needlessly expose people to blood pressure-reduction drugs, all to the benefit of pharmaceutical companies.

Since then, a number of studies have set out to investigate whether people with pre-hypertension are actually at future risk for adverse clinical events. The data for stroke, however, has been conflicting so we decided to compile all the published studies in the scientific literature to date, and using statistical techniques, find out if there was indeed a higher stroke risk, to what extent and whether particular characteristics were associated with that higher risk.

Q: So what do persons with pre-hypertension do? You note in your paper that there is no compelling evidence that drugs used to lower blood pressure actually affect long-term stroke risk.

A: Yes. Right now the best immediate action is behavioral. Young and middle-aged persons should check their blood pressure regularly through scheduled visits to their physician, as well as on their own if possible. If they do fall into the higher range of pre-hypertension, they should take specific steps to modify their lifestyle. Reduce salt intake. Exercise. Maintain normal weight. Modifying one’s lifestyle is relatively safe and could potentially lower not just the risk of future strokes, but possibly other complications of prolonged elevation of blood pressure including heart attacks, heart failure, and kidney disease.

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