**Trials of Hypertension Prevention, Phase II**

**Objective:** Phase II of TOHP (TOHP II) was designed to test the
efficacy of interventions to promote weight loss, sodium reduction, and
the combination of weight loss and sodium reduction in decreasing
diastolic BP, systolic BP, and the incidence of hypertension during a 3-
to 4-year follow-up period in moderately overweight men and women with a
high-normal level of diastolic BP.

**Background:** Between 30% and 40% of all BP-related CVD events occur
in individuals with an average BP below currently defined hypertensive
levels but above the optimal level. A large body of information from
observational studies has identified several determinants of elevated
BP. The corresponding interventional data are less plentiful and much of
what is available reflects experience in small studies with relatively
short periods of follow-up. The initial phase of TOHP (TOHP I) tested
the feasibility and efficacy of 3 separate lifestyle interventions
(weight loss, dietary sodium reduction, and stress management) and 4
separate nutritional supplement interventions (calcium, magnesium,
potassium, and fish oil). The weight loss and sodium reduction groups,
but not the other groups, demonstrated significant decreases in both
systolic and diastolic BP. Number range CHAPTERThe second phase of TOHP
was designed to test the effect of the two most promising interventions
over a longer period of follow-up.

**Design:** Number range CHAPTERPhase II of TOHP was a 2x2 factorial,
with intervention groups of weight loss alone (Weight Loss), sodium
reduction alone (Sodium), and a combination of weight loss and sodium
reduction (Combined) as well as a usual care comparison group.
Participants in each of the four arms were seen at one of the nine
participating clinics every six months for 36 to 48 months. Collection
of final visit data concluded in March of 1995.

**Subjects:** Number range CHAPTER Participants were 30-54 years of age,
with a body mass index representing 110-165% of desirable body weight.
BP was measured at each of 3 screening visits with 3 measurements per
visit. Eligible subjects had an average diastolic BP in the range 83-89
mmHg, with systolic BP \<140 mmHg, and were not on antihypertensive
medication. A total of 2,382 participants were randomized into the
trial. Average age at baseline was 44 years, 66% of participants were
male, and 21% were minority.

**Conclusions:** At six months, compared to usual care, BP decreased
3.7/2.7 mm Hg in the weight loss group, 2.9/1.6 mm Hg in the sodium
reduction group, and 4.0/2.8 mm Hg in the combined group. At 36 months,
BP decreases remained greater in the active intervention groups than in
the usual care group (weight loss, 1.3/0.9 mm Hg; sodium reduction,
1.2/0.7 mm Hg; combined, 1.1/0.6 mm Hg). The incidence of hypertension
was significantly less in each active intervention group than in the
usual care group (Arch Intern Med 1997: 157:657-667). In overweight
adults with high-normal BP, weight loss and reduction in sodium intake,
individually and in combination, were effective in lowering systolic and
diastolic BP, especially in the short-term. Although the effects on
average BP declined over time, reductions in hypertension incidence were
achieved.