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The threshold for treating higher-than-normal blood pressure has been lowered so frequently in past years “having hypertension is (now) virtually synonymous with taking a medication for it,” Canadian and U.S. researchers write in the British Medical Journal.
Up to 40 per cent of adults worldwide have hypertension. More than half of those have “mild” high blood pressure, defined as 140 to 159 systolic pressure and 90 to 99 diastolic. (Systolic measures the pressure in the arteries when the heart beats; diastolic measures pressure in the arteries between heartbeats.)
Complications from untreated high blood pressure may be responsible for up to half of all deaths due to heart disease and stroke worldwide. But the controversy is over when treatment should begin.
According to the authors, the rationale for the continuing push to get blood pressures to “normal” levels is based on a “leap of faith” that even mildly elevated blood pressure in low risk people increases their risk of heart attack and stroke.
However, a Canadian-led review published two years ago involving 11 randomized controlled trials involving nearly 9,000 patients with mild hypertension found those treated with blood pressure lowering drugs were no less likely to develop, or die of coronary heart disease or stroke than patients given a placebo.
Nine per cent of the treatment group stopped the drugs because of side effects such as dizziness and fatigue.
“We’re not saying that we have proven that there is no benefit. We’re saying that it’s unproven that there is a benefit,” said Dr. James Wright, a co-author and coordinating editor of the Cochrane Hypertension Review Group at the University of B.C.
“There’s a growing appreciation of the fact that this treatment is being done in the absence of evidence,” he said.
Today, drugs have become the mainstay of treatment, and high blood pressure has become one of the most lucrative conditions for big pharma: In the U.S. alone, the cost of treating mild hypertension is an estimated $32 billion a year.
“I do think there’s money behind this,” Wright said.
“There’s an incentive on both the part of drug companies for more people to be taking drugs and also some incentives on the part of doctors to be treating more people,” he said. “It’s the most common reason people go to the doctor.”
Blood pressure lowering drugs, which include diuretics, ACE inhibitors and calcium channel blockers, don’t carry a high number of adverse effects, Wright said.
The biggest issue is lowering blood pressure too much, especially in older people, increasing their risk of falls.
Wright and his co-authors argue in the British Medical Journal that drug treatment should be targeted at high-risk patients — those with moderate to severe hypertension (over 160 systolic), as well as those with diabetes, chronic kidney disease or a history of heart attack or stroke.
For mild hypertension in low risk people (those with no known history of heart attack or stroke) the focus should be lifestyle changes. Exercise, low sodium diets, diets high in fruits, vegetables and low-fat milk products and reducing alcohol to no more than one to two drinks a day have all been shown to lower blood pressure, Wright said.
People should be encouraged to measure their blood pressure at home and doctors should be upfront with their patients about the lack of known benefit treating low risk patients with blood pressure drugs, the authors write.
“They should be advised that this is a range where we don’t have evidence that the benefit of treatment outweighs the harms,” Wright said.