title: Baseline characteristics of participants in phase I of the Trials of Hypertension Prevention.
abstract: Phase I of the Trials of Hypertension Prevention was designed to test the effectiveness and safety of three life-style (weight loss, sodium restriction, and stress management) and four nutrition supplement (calcium, magnesium, potassium, and fish oil) interventions in reducing diastolic blood pressure (DBP) in persons with a high-normal blood pressure. A total of 2182 persons with a DBP between 80 and 89 mm Hg met the eligibility criteria for participation in phase I and were randomized to one of the active intervention or control treatment groups. Most were white (82%), male (70%), married (76%), nonsmoking (88%), college graduate (53%), full-time employees (91%). The average blood pressure prior to entry into the trial was 124.9 mm Hg systolic and 83.8 mm Hg diastolic. A variety of baseline observations, including sociodemographic characteristics, personal and family medical history, health habits, diet, and biologic measurements, were documented before randomization and compared among the seven active intervention and control groups. As might be expected in a randomized trial of this sample size, the distribution of measured baseline characteristics was virtually identical in the treated and control groups. Based on this finding and the knowledge that randomization procedures were implemented without deviation from the phase I protocol, it is probable that unknown potential confounders were also equally distributed at entry into the study. Given the achievement of high rates of follow-up, subsequent differences in blood pressure are unlikely to have been due to baseline differences between the active treatment and control groups, and can probably be attributed to effects of the active interventions.
authors.affiliation: Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins Medical Institutions, Baltimore, MD.
authors.forename: P K
authors.initials: PK
authors.lastname: Whelton
authors.forename: P R
authors.initials: PR
authors.lastname: Hebert
authors.forename: J
authors.initials: J
authors.lastname: Cutler
authors.forename: W B
authors.initials: WB
authors.lastname: Applegate
authors.forename: K A
authors.initials: KA
authors.lastname: Eberlein
authors.forename: M J
authors.initials: MJ
authors.lastname: Klag
authors.forename: M E
authors.initials: ME
authors.lastname: Keough
authors.forename: S
authors.initials: S
authors.lastname: Hamill
authors.forename: N O
authors.initials: NO
authors.lastname: Borhani
authors.forename: J
authors.initials: J
authors.lastname: Hollis
mesh_terms: D000328:Adult; D001794:Blood Pressure; D004032:Diet; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology / Q000517:prevention & control / Q000628:therapy*; D008019:Life Style; D008297:Male; D008875:Middle Aged