A recent study published in the July 2007 issue of the journal Epidemiology appeared to weaken the link between obesity and high blood pressure. The researchers set out to assess blood pressure (BP) and its relationship with body mass index (BMI) over a 15-year interval in the Seychelles, a rapidly developing country in the African region.
They conducted two independent cross-sectional examination surveys in 1989 (n = 1081) and 2004 (n = 1255) using representative samples of the population age 25-64 years. They found that between 1989 and 2004, mean BP (mm Hg) decreased slightly (from 133/87 to 131/86 in men and from 127/82 to 124/81 in women), with little change in the age-standardized prevalence of high BP (BP >=140/90 or current treatment; from 45% to 44% in men and from 34% to 36% in women).
They also observed that during the same period, awareness among participants with high blood pressure markedly increased (from 42% to 64%), as did treatment (22% to 59%), and control (3% to 20%), yet the prevalence of overweight (BMI >=25 kg/m2) increased from 39% to 60%. Additionally, the linear relationship between BMI and BP was markedly weaker in 2004 than in 1989, antihypertensive treatment, weight, and age, regardless.
The research also showed that among those untreated, a BMI increment of 1 kg/m2 was linked with an elevation of 2.0/1.5 mm Hg of systolic/diastolic BP in 1989 but only 1.3/1.0 mm Hg in 2004. The authors concluded based on these findings that the link between BMI and BP has decreased over time, although acknowledged that further research would facilitate understanding of its underlying reasons and its implications for an otherwise increasing prevalence of obesity worldwide.
Danon-Hersch, Nadia; Chiolero, Arnaud; Shamlaye, Conrad; Paccaud, Fred; Bovet, Pascal. Decreasing Association between Body Mass Index and Blood Pressure over Time. Epidemiology. 18(4):493-500, July 2007