This was the largest—and most detailed—study ever conducted to examine these questions. The researchers combined data on individuals who had participated in a randomized clinical trial and conducted a meta-analysis. The study included 348,854 participants from 48 trials.
Participants were divided into two groups: those with a prior diagnosis of cardiovascular disease and those without. Each group was divided into seven subgroups based on systolic blood pressure at study entry (less than 120, 120-129, 130-139, 140-149, 150-159, 160-169, 170 and above mmHg).
Over an average four years of follow-up, each 5 mmHg reduction in systolic blood pressure lowered the relative risk of major cardiovascular events by about 10%. The risks for stroke, ischaemic heart disease, heart failure and death from cardiovascular disease were reduced by 13%, 7% and 14% and 5%, respectively.
