October 13, 2008 (Bethesda, MD) — A new report looking at hypertension during two time periods 10 years apart has found that more US adults have high blood pressure than ever before. The prevalence has increased from almost 25% during the first period surveyed (1988–1994) to 28.9% during the second period (1999–2004). The findings, by Dr Jeffrey A Cutler (National Heart, Lung, and Blood Institute [NHLBI], Bethesda, MD) and colleagues, are published online October 13, 2008 in Hypertension [1].

Coauthor Dr Paul D Sorlie (NHLBI) told heartwire: "This is something we are not pleased to see." However, there is also some good news, he said. "Awareness, treatment, and control of hypertension have also improved, higher than ever reported, which we believe is a good thing."

Knowing the magnitude of the relationship between obesity and hypertension, we can say that control/prevention of obesity has got to be a major focus now.

Sorlie said the increase in obesity in the US population between the same two time periods "accounts for almost all of the increase in blood pressure, associationwise, in men," but that this is less true for women, for reasons that are not fully understood. "Knowing the magnitude of the relationship between obesity and hypertension, we can say that control/prevention of obesity has got to be a major focus now, because it makes such a contribution to the increase seen in this period."

In an accompanying editorial [2], Dr Theodore A Kotchen (Medical College of Wisconsin, Milwaukee) agrees: "The analysis of Cutler et al provides added impetus for preventing obesity and encouraging weight loss for the overweight as strategies for hypertension prevention. This is particularly relevant because the prevalence of childhood obesity has increased several-fold in the past decade."

Prevalence of Hypertension Rising Twice as Fast in Women

The NHLBI researchers compared the hypertension findings of the third National Health and Nutrition Examination Survey (NHANES III), which ran from 1988 to 1994, with data from the first six years (1999 to 2004) of the current NHANES, which collects information continuously in two-year blocks. They examined data from 16 351 NHANES III respondents and 14 430 people surveyed from 1999 to 2004, all 18 years or older.

The age-standardized prevalence rate for hypertension rose from 24.4% to 28.9%. Being overweight or obese accounted for part but not all of the increase in high blood pressure among different age, sex, and race/ethnicity groups.

The increase was greater for women than for men--the proportion of women with hypertension is rising two times faster than that of men--and occurred in all racial/ethnic groups.

Depending on sex and race/ethnicity, from 20% to 80% of the increase could be accounted for by increasing body-mass index, the researchers say.

"We see that much of the magnitude in men is accounted for by obesity, but [this is less true for] women, possibly because of some unexplored changes in risk factors for hypertension," Sorlie said.

Factors other than obesity that likely contributed to the increase in hypertension include the fact that more people are living with high blood pressure than dying from it. "Control is better, so maybe we are seeing a lot more people surviving, not going on to have, for example, heart attacks," Sorlie suggested.

Other things that could have contributed to the rises seen are increasingly sedentary lifestyles, increasing consumption of sodium, and lack of access to health-plan coverage or preventive services, the researchers speculate.

Focus Now on Women and Mexican Americans

In terms of awareness among hypertensive people, there was a modest increase overall, from 68.5% to 71.8% (p=0.04), with awareness generally improving more for men (from 61.6% to 69.3%) and staying more or less the same for women. Awareness rates remained higher for women than for men overall, but the difference has narrowed considerably.

Treatment improved also, from 53.1% to 61.4%, as did control of hypertension, from 26.1% to 35.1% (p<0.001 for both). The greatest increases occurred among non-Hispanic white men and non-Hispanic blacks, especially men (although young black men still had low control rates, at 20.3%).

Black women, however, had the highest awareness and treatment, and almost the highest control of their hypertension overall, Sorlie said.

He believes this indicates that targeting of certain ethnic groups, because of the higher prevalence of hypertension among them, has been successful: "They seem to be getting the message."

Among whites, however, men now have better control of their hypertension than women, "which is a sort of reversal," he commented. "Although this was not statistically significant, it's interesting to note that this direction has changed for the first time," he said.

A better understanding of what is impeding progress in the treatment of hypertension in women, especially white women, is needed, he added.

But the group on whom most focus is needed right now is Mexican Americans, Sorlie stressed. Although there was an improvement in treatment and control rates in this ethnic group, these rates remain "far from desirable" and substantially lower than for other racial/ethnic groups, he said (at 47.4% for treatment and 24.3% for control of hypertension).

Control rates are particularly poor among younger Mexican American men (at 16%) and older women (19%).

"Mexican Americans need a tremendous amount of improvement in awareness, treatment, and control of hypertension," he stressed. "It may be that a lot of that is related to healthcare access." This demonstrates a strong need for the use of focused efforts in this subpopulation, he added.

Kotchen agrees: "Effective, culturally sensitive strategies will have to be developed to achieve the Healthy People 2010 target goal of a hypertension control rate of 50%, and this will require better understanding of the barriers."