Minimising side-effects is seen as critical to ensure that people keep taking their medication for a condition that is widely known as the 'silent killer' because it has few symptoms.
Several previous studies have suggested that low-dose combinations may be particularly effective because they give the best trade-off between fewer side-effects and most blood pressure lowering benefits.
The latest study published in the journal Hypertension compared the performance of medication containing 1 or more of 5 different types of blood-pressure lowering drugs at lower doses with that of single medication at a standard dose or a placebo.
The researchers analysed 42 trials involving 20,284 people who were being treated for high blood pressure on various doses of medications or taking no medication. The review included many different types of medications from the main classes on offer.
They found that:
Two medications in combination, each at a quarter dose, was just as effective as one blood pressure lowering medication at standard dose.
Four medications in combination, each at a quarter dose, was nearly twice as effective as taking a single blood pressure lowering medication at the standard dose. However this result was based on only 2 small trial.
The side effects from single and dual quarter-dose therapies were about the same as from placebo and much less than from a standard dose of a single blood pressure lowering medication.
'Check with your GP'
In an emailed comment, Katharine Jenner from Blood Pressure UK, says: "It is estimated that between 50 to 80% of patients with high blood pressure do not take all of their prescribed medicine, putting them at risk of having a stroke or heart attack. Clearly any measures that will encourage people to get their blood pressure under control will save lives.
"However, most people on the correct treatment do not actually feel side-effects from their blood pressure medication, and lower dosages may mean more visits to their GP to check it is working properly.
"We would be interested to see how this will work in practice for the millions of people living with high blood pressure."
Dr Mike Knapton, associate medical director at the British Heart Foundation comments by email: “It’s thought that treatments could be improved for around a third of patients with high blood pressure which is why studies like this are so important. However, more research is needed to test the hypothesis that taking low doses of multiple drugs, rather than higher doses of one drug, could be more effective."
Efficacy and Safety of Quarter-Dose Blood Pressure–Lowering Agents: A Systematic Review and Meta-Analysis of Randomized Controlled Trials, Bennett A et al, Hypertension
American Heart Association
Blood Pressure UK
British Heart Foundation
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