Association Between BMI and Blood Pressure Has Decreased Since 1989

NEW YORK (Reuters Health) Jul 02 - The association between body mass index (BMI) and blood pressure (BP) has decreased over time, according to a study published in the July issue of Epidemiology. The results suggest that obesity may not have as much of an impact on cardiovascular disease as previously thought.

"High blood pressure is a leading cause of the global burden of disease," Dr. Pascal Bovet, of the University of Lausanne, Switzerland, and colleagues write. "The prevalence of hypertension, and of several other conditions (including diabetes), is considered to be linked to the worldwide epidemic of obesity."

The researchers examined trends over time in mean BP, prevalence, awareness, treatment, and control of high BP. They assessed the relationship between BP and BMI over a 15-year interval in the Seychelles, a country in the African region. Their analysis was based on two independent cross-sectional surveys conducted in 1989 (n = 1081) and 2004 (n = 1255) using representative samples of the population between the ages of 25 and 64 years.

There was a slight decrease in mean BP between 1989 and 2004 in both men (from 133/87 mmHg to 131/86 mmHg) and women (from 127/82 mmHg to 124/81 mmHg). There was little change in the age-standardized prevalence of high BP during this time (from 45% to 44% in men and from 34% to 36% in women). Among subjects with high BP, marked increases were observed during this time in awareness (42% to 64%), treatment (22% to 59%), and control (3% to 20%).

Overweight, defined as a BMI of at least 25, increased from 39% to 60% between 1989 and 2004. However, the association between BMI and BP decreased "substantially and consistently between 1989 and 2004, irrespective of sex and antihypertensive treatment," Dr. Bovet's team writes. Systolic BP increased by 0.71 mmHg less and diastolic BP increased by 0.50 mm Hg less in 2004 than in 1989 for each unit of BMI.

"If confirmed, a decreasing association between BMI and BP over time could imply that the impact of the overweight epidemic on cardiovascular disease might be less important than predicted," the authors conclude. "This decreased relationship could also help to explain the current favorable trends in cardiovascular disease (declining incidence) observed in many countries despite the increasing prevalence of obesity."

Epidemiology 2007;18:493-500.

Source: http://www.medscape.com/viewarticle/559177?src=mp