May 20, 2009 |
Blood pressure lowering drugs should be offered to anyone old enough to be at risk of a heart attack or stroke (or who is otherwise known to be at risk), regardless of their blood pressure, according to the largest analysis of blood pressure trials to date, published on bmj.com today.
Cardiovascular disease is the leading cause of death throughout the world. For 65 year olds in England and Wales the risk of having a heart attack in the next 10 years is about 10% for men and 5% for women. The increase in blood pressure during a person’s life, which affects nearly everyone, is one of the main reasons for strokes and heart attacks being so common.
Despite the widespread use of blood pressure lowering drugs and the results of many randomised trials, uncertainty remains about which drugs to use and whom to treat. For example, does the preventive effect of drugs differ in people with and without a history of heart disease? And should blood pressure lowering drugs be limited to people with high blood pressure?
To answer these questions, Professor Malcolm Law and colleagues from the Wolfson Institute of Preventive Medicine at Barts and The London School of Medicine analysed the findings of 147 blood pressure trials published between 1966 and 2007, involving 464,000 people.
The results show that using any one of the main classes of blood pressure lowering drugs at standard dose reduced fatal and non-fatal heart attacks by about a quarter and stroke by about a third. Heart failure was also reduced by about a quarter. The reductions in disease were similar in people with and without clinical cardiovascular disease and regardless of blood pressure before treatment.
All the classes of blood pressure lowering drugs had a similar effect for a given reduction in blood pressure that was accurately predicted from epidemiological studies of blood pressure and subsequent disease with two exceptions?an extra protective effect of beta-blockers given shortly after a heart attack and a small additional effect of calcium channel blockers in preventing stroke.
And combining the results with two previously published studies showed that three drugs together, each at low dose to minimise side effects, could increase the preventive effect, reducing heart attacks by about 45% and stroke by about 60%.
Professor Malcolm Law said “The results show that blood pressure lowering drugs should be offered to anyone at sufficient risk to benefit from treatment, whatever their reason for being at risk.” However, the exact age range for being most at risk of heart attack and stroke could not be defined precisely from this study, which only looked at randomised trials in people aged 60.
In an accompanying editorial, Richard McManus from the University of Birmingham and Jonathan Mant from the University of Cambridge, say that these findings reinforce the view that treatment to lower blood pressure should be offered on the basis of risk, regardless of blood pressure. These data support the use of a polypill to lower the risk of cardiovascular disease in people at high risk without first checking their blood pressure, they add.