THE COMPARATIVE STUDY OF ANTIHYPERTENSIVE TREATMENTS (CSAT): BACKGROUNDS, METHODS, AND THE PRELIMINARY RESULTS (INTERIM REPORT)

The "Comparative Study of Antihypertensive Treatments"-CSA T is a placebo-controlled, randomized, double-blind clinical trial, with the primary objective of comparing the efficacy of different pharmacological treatments of hypertension. Drug side-effects, patient compliance, and alterations in the patients' quality of life are also compared. Subjects with mild to moderate diastolic hypertension aged above 30 are randomized into either of 5 groups receiving methyldopa, atenolol, nifedipine, triamterene-H, or placebo. After a dose titration phase, the minimum drug dose required to achieve a therapeutic goal of less than 91 mmHg for diastolic blood pressure (DBP) is determined, and the patient then enters a maintenance phase of 6 months. This report presents the preliminary results of drug efficacy in 136 subjects who have completed the dose titration phase. Age, sex, baseline systolic blood pressure (SBP) and baseline DBP were all well balanced across placebo and drug groups: mean age ± SD = 51.9 ± 9.2 years sex distribution: 56.6% males: mean DBP ± SD = 98.5 ± 5.4 mmHg mean SBP ± SD = 152.1 ± 14.4 mmHg (SD = standard deviation, SBP and DBP values were measured in the sitting position). SBP and DBP reduction in the active treatment groups (mean ± SE: 17.8 ± 1.4 mmHg for SBP, 12.4±0.7 mmHg for DBP) were significantly greater than in the placebo group (mean± SE: 7.9± 1.6 mmHg for SBP, 7.23 ±0.9 mmHg forDBP) at the end of the dose titration phase (P < 0.00001). There was greater SBP reduction with atenolo1 23.9 ± 3.2 mmHg) than with either nifedipine (12.5 ± 2.3 mmHg) or triamterene-H (16.2 ± 2.7 mmHg), P<0.05. This difference was not observed in patients aged above 50, but was significant in the below 50 age group. Pharmacological treatment was more efficacious in SBP reductionin women than in men (22 ±2.1 mmHg in women versus 14.0± 1.7 mmHg in men, P<0.01). No similar difference between the two sexes was detected in the placebo group. This interim report of the CSAT emphasizes the importance of pharmacological therapy, and depicts significant differences in the antihypertensive efficacy of various drug groups. Establishing new research centers and reaching desired sample sizes are currently being undertaken.