Efficacy of different drug classes used to initiate antihypertensive treatment in black subjects: results of a randomized trial in Johannesburg, South Africa

Abstract

Background: Thiazides are recommended to initiate antihypertensive drug treatment in black subjects.

Objective: To test the efficacy of this recommendation in a South African black cohort.

Methods: Men and women (N = 409), aged 18 to 70 years, with a mean ambulatory daytime diastolic blood pressure between 90 and 114 mm Hg, were randomized to 13 months of open-label treatment starting with the nifedipine gastrointestinal therapeutic system (30 mg/d, n = 233), sustained-release verapamil hydrochloride (240 mg/d, n = 58), hydrochlorothiazide (12.5 mg/d, n = 58), or enalapril maleate (10 mg/d, n = 60). If the target of reducing daytime diastolic blood pressure below 90 mm Hg was not attained, the first-line drugs were titrated up and after 2 months other medications were added to the regimen.

Results: While receiving monotherapy (2 months, n = 366), the patients' systolic and diastolic decreases in daytime blood pressure averaged 22/14 mm Hg for nifedipine, 17/11 mm Hg for verapamil, 12/8 mm Hg for hydrochlorothiazide, and 5/3 mm Hg for enalapril. At 2 months the blood pressure of more patients treated with nifedipine was controlled: 133 (63.3%, P</=.03) vs 20 (39.9%) receiving verapamil, 21 (40.4%) receiving hydrochlorothiazide, and 11 (20.8%) receiving enalapril. At 13 months (n = 257), more patients (P<.001) continued receiving monotherapy with nifedipine (94/154 [61.0%]) or verapamil (22/35 [62.9%]) than hydrochlorothiazide (10/39 [25.6%]) or enalapril (1/29 [3.4%]). A sustained decrease of left ventricular mass (P<.001) with no between-group differences was achieved at 4 and 13 months.

Conclusions: In contrast to current recommendations, calcium channel blockers are more effective than thiazides as initial treatment in black subjects with hypertension. If treatment is started with thiazides or converting-enzyme inhibitors, combination therapy is more likely to be required to control blood pressure and reduce left ventricular mass.