The PROGRESS Trial: Preventing Strokes by Lowering Blood Pressure in Patients With Cerebral Ischemia

those of the 4 previous trials combined (2742). The active treatment consisted of 1 or 2 drugs: always the angiotensin- converting enzyme (ACE) inhibitor perindopril (4 mg per day), in 58% of cases also the diuretic agent indapamide (mostly 2.5 mg per day). The choice between combined treatment (or double placebo) and perindopril alone (or single placebo) was left to the discretion of the physician. Importantly, existing antihyperten- sive treatment was continued in an unchanged fashion (50% of patients in the 2-drug group, 51% in the perindopril-only group); the same applied to other drugs such as antiplatelet agents. After an average follow-up period of almost 4 years in the PROGRESS trial, the rate of major vascular events (vascular death, nonfatal stroke, or vascular death) was 5.5% per annum in the placebo group. This hazard was reduced to an annual rate of 4.1%, ie, by 26% (95% CI 16% to 34%) in all patients on active drug treatment (combined or single). This result was driven mainly by the patients on combined treatment (40% reduction of major vascular events, 95% CI 29% to 49%), in whom blood pressure was lowered by a mean of 12/5 mm Hg. There was a nonsignificant hazard reduction of 4% (95% CI 15% to 20%) by perindopril alone, associated with a mean blood pressure reduc- tion of 5/3 mm Hg. The difference between the effects of combined and single drug treatment remained the same after correction for baseline imbalances. Patients with a baseline blood pressure above 160/90 mm Hg benefited somewhat more (29% reduction of major vascular events, 95% CI 16% to 40%) than nonhypertensive participants (24%, 95% CI 9% to 37%); this difference was attributable almost exclusively to the perindopril-only group. Strokes were prevented to the same