The benefits of a systolic blood pressure (BP) below 150-160 mmHg are well established; whether a systolic BP of less than 140 mmHg provides additional benefits remains controversial. This study was designed to compare the 2-year effect of a strict treatment to maintain systolic BP below 140 mmHg (group A) and that of a mild treatment to maintain systolic BP at between 140 and below 160 mmHg (group B). The study design followed the Prospective Randomized Open Blinded, End-point (PROBE) study. The subjects were elderly patients (65-85 years old) who consistently had a systolic BP of 160 mmHg or higher. The baseline drug was efonidipine hydrochloride (efonidipine), a long-acting dihydropiridine calcium antagonist. The primary endpoints were stroke, cardiac disease, vascular disease, and renal failure. After a run-in period of 2 to 4 weeks, 2,165 patients were assigned to group A and 2,155 patients to group B. There were no significant differences between the groups in sex, age, baseline BP, or other cardiovascular risk factors. The systolic BP was 7.2 mmHg lower (p<0.0001) and the diastolic BP 2.4 mmHg lower (p<0.0001) in group A than in group B after 12 months of treatment. As of this interim analysis, primary endpoints have occurred in 87 patients (stroke in 58 patients, cardiac disease in 27 patients, occlusive arterial disease in 1 patient, and renal failure in 1 patient). Five patients have died of stroke and 2 patients of myocardial infarction. The primary-endpoint-related morbidity rate was 20.9/1,000 patient-years, and the mortality rate was 1.7/1,000 patient-years. Currently available results indicate that this study, one of the largest randomized trials of antihypertensive therapy in elderly patients in Japan, was conducted safely. The final results are expected to provide important and practical information for the management of hypertension in elderly patients.
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