FEASIBILITY AND EFFICACY OF SODIUM REDUCTION IN THE TRIALS OF HYPERTENSION PREVENTION, PHASE-I

Phase I of the Trials of Hypertension Prevention was a multicenter, ra ndomized trial of the feasibility and efficacy of seven nonpharmacolog ic interventions, including sodium reduction, in lowering blood pressu re in 30- to 54-year-old individuals with a diastolic blood pressure o f 80 to 89 mm Hg. Six centers tested an intervention designed to reduc e dietary sodium to 80 mmol (1800 mg)/24 h with a total of 327 active intervention and 417 control subjects. The intervention consisted of e ight group and two one-to-one meetings during the first 3 months, foll owed by less-intensive counseling and support for the duration of the study. The mean net decrease in sodium excretion was 43.9 mmol/24 h at 18 months. Women had lower sodium intake at baseline and were therefo re more likely to decrease to less than 80 mmol/24 h. Black subjects w ere less likely to decrease to less than 80 mmol/d, independent of sex or baseline sodium excretion. The mean (95% confidence interval) net decrease associated with treatment was -2.1 (-3.3, -0.8) mm Hg for sys tolic blood pressure and -1.2 (-2.0, -0.3) mm Hg for diastolic blood p ressure at 18 months (both P<.01). Multivariate analyses indicated a l arger systolic blood pressure effect in women (-4.44 versus -1.23 mm H g in men), adjusted for age, race, baseline blood pressure, and baseli ne 24-hour urinary sodium excretion (P=.02). Dose-response analyses in dicated an adjusted decrease of -1.4 mm Hg for systolic blood pressure and -0.9 mm Hg for diastolic blood pressure for a decrease of 100 mmo l/24 h in 18-month sodium excretion. These results support the utility of sodium reduction as a population strategy for hypertension prevent ion and raise questions about possible differences in dose response as sociated with gender and initial level of sodium intake.