A large-scale analysis of 48 randomised trials, published in The Lancet, found a 5mmHg reduction in systolic blood pressure reduced the risk of major cardiovascular events by about 10%, irrespective of previous diagnoses of cardiovascular disease, and even at normal or high–normal blood pressure values.
'Our findings are of great importance to the debate concerning blood pressure treatment', said lead author Professor Kazem Rahimi, from the University of Oxford.
'This new and best available evidence tells us that decisions to prescribe blood pressure medication should not be based simply on a prior diagnosis of cardiovascular disease or an individual’s blood pressure level. Instead, medication should be viewed as an effective tool for preventing cardiovascular disease in people at increased risk of developing heart disease or stroke. Clinical guidelines should be changed to reflect these findings.'
The Blood Pressure Lowering Treatment Triallists’ Collaborators pooled data from 344,716 adults (average age 65 years) in 48 randomised trials to explore the effects of blood pressure-lowering medications. Participants were separated into two groups: those with a prior diagnosis of cardiovascular disease (157,728 participants – secondary prevention group) and those without (186,988 – primary prevention group, without cardiovascular disease).
Each group was then divided into seven subgroups based on levels of systolic blood pressure at study entry. Around 20% of participants with prior cardiovascular disease and 8% of those who had never had cardiovascular disease had normal or high-normal systolic blood pressure at the start of the trials (systolic blood pressure <130 mmHg).
Over a median of 4 years' follow-up, 42,324 participants had at least one major cardiovascular event (heart attack, stroke, heart failure, or death from cardiovascular disease). For every 5mmHg reduction in systolic blood pressure, the risk of a major cardiovascular event fell by around 10%, stroke by 13%, heart failure by 13%, ischaemic heart disease by 8%, and death from cardiovascular disease by 5%.
The beneficial effects of antihypertensive treatment did not differ based on a history of having had cardiovascular disease or the level of blood pressure at study entry.
The authors concluded that a fixed degree of pharmacological blood pressure lowering is similarly effective for primary and secondary prevention of major cardiovascular disease, 'even at blood pressure levels currently not considered for treatment'.
Calling for revision of clinical guidelines globally, the researchers say their findings provide evidence against the current practice of restricting antihypertensive treatment to people with higher than average blood pressure values.
Professor Rahimi added: 'We’re not saying that everyone must begin treatment. The decision will depend on an individual’s risk factors for developing cardiovascular disease, the potential for side effects and patient choice.'