Potential new blood pressure guidelines published Wednesday in the Journal of the American Medical Association are making waves in the field of cardiovascular medicine: Some Canadian experts are worried that the news could confuse patients and lead to an increase in heart attacks and stroke.
The widely held threshold for a person to be diagnosed with high blood pressure is 140 over 90. People with this blood pressure reading or higher are advised to change their diet and lifestyle habits and possibly initiate drug therapy to lower the pressure on the heart.
But for adults 60 years and older, the panel of American experts who wrote the paper recommended a higher threshold – 150 over 90 – as more reasonable, based on evidence that few additional benefits come with more aggressive treatment.
Canadian hypertension expert Dr. Ernesto Schiffrin said he expects to be fielding many patient queries on the recommendation.
When looking at the over-60 demographic, he says the JAMA authors, led by Paul James of the University of Iowa, didn't take into account the broad range of risk factors many patients have in addition to high blood pressure.
"They didn't consider that many patients, after age 60, have elevated cholesterol, they may be smokers, they may be overweight or obese. For those patients, perhaps a majority of patients above age 60, recommending blood pressures under 150 may be under-treating them," says Schiffrin, who works at the Sir Mortimer B. Davis-Jewish General Hospital in Montreal.
And since Canada has been doing a good job of treating hypertension, Schiffrin says it would be a shame for physicians to take the American advice and risk having patients with blood pressure between 140 and 150 over 90 suffer heart attacks or strokes.
Canadians already have rigorous evidence-based guidelines updated annually by the non-profit organization Hypertension Canada, Schiffrin says. He is the president of Hypertension Canada. According to Hypertension Canada, almost six million people in Canada – that's about 1 in 5 adults – live with hypertension. And rising blood pressure over the long term is known to cause atherosclerosis, or hardening of the arteries, which is a major risk for premature death (before the age of 65), according to Hypertension Canada.
Schiffrin says the Canadian guidelines do include a recommendation aimed at those "rare individuals," who don't exhibit other risk factors: 160 over 100.
"There are very few people who have elevated blood pressure and no additional risk factors," says Schiffrin, who is also the Canada Research Chair in hypertension and vascular research at the Lady Davis Institute for Medical Research and a professor in the department of medicine at McGill University.
Furthermore, there is also a Canadian age-based recommendation for people over 80 which takes into account both a UK trial that has shown benefits to lowering blood pressure to 150 systolic or less (at that age, the systolic pressure - which occurs when your heart contracts rather than the diastolic, when the heart is relaxed - is the key measure physicians look at) and the fact that doctors worry about the elderly being frail and at risk of falls.
Still, some experts say allowing more wiggle room in the blood pressure measurements of those 60 and older may be an idea worth exploring. Dr. Peter Liu, the scientific director of the University of Ottawa Heart Institute, says the spotlight on this "grey area" in hypertension treatment highlights if not a change, the need for individualized treatment.
"As we get older our blood pressure increases – this is just part of the aging process. If that's the only thing that you have, then trying to bring down blood pressure may not be realistic or necessary."
While the JAMA paper didn't mention side-effects, Liu says for some patients, the side effects of blood pressure medications may outweigh the benefits. Side effects can include swelling of the legs and dizziness, which could lead to falls.
Adding to the guideline controversy is the fact that the panel who wrote the recommendations is acting independently, after being relieved of their duties by their sponsoring body, the National Heart, Lung, and Blood Institute (NHLBI), one of the National Institutes of Health government agencies of the U.S. Department of Health and Human Services. This June, NIH discontinued the project, looking to other organizations such as the American Heart Association to create guidelines instead.
Liu says despite the fuss south of the border, all physicians and cardiologists would do well not to get too caught up in the numbers.
"At the end of the day, guidelines are guidelines. At the patient-doctor-interaction level you want to personalize these things for the patient."
Editor's Note: Dr. Ernesto Schiffrin is the president of Hypertension Canada. This version has been updated