Long-term effects of weight loss and dietary sodium reduction on incidenceof hypertension

To examine the long-term effects of weight loss and dietary sodium reductio n on the incidence of hypertension, we studied 181 men and women who partic ipated in the Trials of Hypertension Prevention, phase 1, in Baltimore, Md. At baseline (1987 to 1988), subjects were 30 to 54 years old and had a dia stolic blood pressure (BP) of 80 to 89 mm Hg and systolic BP <160 mmHg. The y were randomly assigned to one of two 18-month lifestyle modification inte rventions aimed at either weight loss or dietary sodium reduction or to a u sual care control group. At the posttrial follow-up (1994 to 1995), BP was measured by blinded observers who used a random-zero sphygmomanometer. Inci dent hypertension was defined as systolic BP greater than or equal to 160 m m Hg and/or diastolic BP greater than or equal to 90 mm Hg and/or treatment with antihypertensive medication during follow-up. Body weight and urinary sodium were not significantly different among the groups at the posttrial follow-up, After 7 years of follow-up, the incidence of hypertension was 18 .9% in the weight loss group and 40.5% in its control group and 22.4% in th e sodium reduction group and 32.9% in its control group. In logistic regres sion analysis adjusted for baseline age, gender, race, physical activity, a lcohol consumption, education, body weight, systolic BP, and urinary sodium excretion, the odds of hypertension was reduced by 77% (odds ratio 0.23; 9 5% confidence interval 0.07 to 0.76; P=0.02) in the weight loss group and b y 35% (odds ratio 0.65; 95% confidence interval 0.25 to 1.69; P=0.37) in th e sodium reduction group compared with their control groups. These results indicate that lifestyle modification such as weight loss may be effective i n long-term primary prevention of hypertension.