NEW YORK (Reuters Health) - It seems that the association between body mass index (BMI) and high blood pressure or hypertension has decreased since 1989, researchers say. The finding suggests that obesity may not have as much of an impact on heart-related 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 in the medical journal Epidemiology. "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 in blood pressure and BMI over a 15-year interval in the Seychelles. Their analysis was based on two independent surveys conducted in 1989 and 2004 using representative samples of the population between the ages of 25 and 64 years.
There was a slight decrease in average blood pressure between 1989 and 2004 in both men and women. The prevalence of high blood pressure changed little during this time -- from 45 to 44 percent in men and from 34 to 36 percent in women.
The percentage of people who were overweight, defined as a BMI of 25 or more, increased from 39 percent to 60 percent between 1989 and 2004.
However, the association between BMI and BP decreased "substantially and consistently" between 1989 and 2004, irrespective of sex, Bovet's team writes.
"If confirmed, a decreasing association between BMI and blood pressure over time could imply that the impact of the overweight epidemic on cardiovascular disease might be less important than predicted," the investigators 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," they point out
SOURCE: Epidemiology, July 2007.