New blood pressure rules may harm some
Study: Patients with lower risk unlikely to benefit
New blood pressure guidelines, touted for the lives they should save, would do more harm than good in some patients, according to a Houston-led study that analyzed the impact of the stricter classification system.
Dr. Robert Phillips, chief medical officer at Houston Methodist Hospital, and his team of researchers argue that while patients at higher risk for cardiovascular disease will benefit from the new guidelines, starting drug treatment in those whose risk isn’t as great is likely to cause them side effects, such as kidney damage and loss of consciousness.
“While more than 100,000 U.S. deaths could be averted annually by implementing more aggressive treatments, you’re going to get serious, adverse events too,” said Phillips, a
Methodist specialist in hypertension and cardiovascular disease and the paper’s lead author. “This presents clinicians and patients with a dilemma, trading one clinically significant condition for another. That’s why you need to reserve such treatment for people who need it the most.”
The team used statistical modeling to show as many as 10 million people would receive unnecessarily aggressive and potentially harmful blood pressure treatments under the guidelines issued last fall. Their paper was published this week in the Journal of the American College of Cardiology, the same publication that printed the guidelines.
High blood pressure, or hypertension, is the leading cause of death worldwide and the secondleading cause of preventable death in the United States, after cigarette smoking. It leads to cardiovascular disease, strokes, severe kidney disease and other maladies that kill millions of Americans every year.
The new guidelines, written by a panel of 21 scientists and health experts and issued by the American Heart Association and American College of Cardiology in November, redefine high blood pressure as 130/80, down from the old standard of 140/90. (The top, systolic, number refers to the pressure on blood vessels when the heart contracts; the lower, diastolic, number to the pressure when the heart relaxes between beats.)
Numbers have doubled
The change has increased the number of Americans with high blood pressure from 72 million to 103 million, or from 32 percent of adults to 46 percent. The number of men under 45 with the condition has doubled, and the number of women in the same group has doubled.
Phillips argues the best strategy would be to place on medication only a subset of patients with blood pressure between 130/80 and 140/90, those who have at least an 18.2 percent risk of a cardiovascular event in the coming 10 years, according to information doctors plug into a commonly used formula. The new guidelines call for the implementation of drug therapy for anyone in the 130/80 to 140/90 window with a 10 percent risk.
Under the guidelines, those whose blood pressure is between 130/80 and 140/90 and whose risk factor is under 10 percent would not need medication right away and could rely on healthier lifestyles — diet and exercise — to reduce their numbers.
Prior to the new guidelines, most people with blood pressure in the 130/80 to 140/90 window would not be taking medication. Many still aren’t.
The team calculated those numbers based on modeling they developed and applied to a 2015 federal study of more than 9,000 people that showed bringing systolic blood pressure below 120 rather than the long recommended 140 very significantly reduced the risk of heart and attack and stroke.
Phillips emphasized he absolutely favors aggressive treatment for patients with blood pressure of 140/90 or greater. He said the last thing he’d want would be for people to misinterpret the paper’s conclusion and think getting below 130/80 shouldn’t be the goal.
More adverse events
But Phillips said the downside of fully implementing the new guidelines would be an additional 88,700 cases of acute kidney injury or failure, which occurs when low blood pressure causes an inadequate flow of blood to the body’s organs; 56,100 episodes of abnormally low pressure, which also can result in dizziness and falls; 34,400 episodes of syncope, a temporary loss of conscious caused by a fall in blood pressure; and 43,400 episodes of electrolyte abnormalities, which can cause muscle spasm, weakness, twitching or convulsions.
Such adverse events can be caused by either the medication itself or a lowering of blood pressure to too low a level, said Phillips.
The study findings were supported in an accompanying editorial by Dr. William White, past president of the American Society of Hypertension. He wrote that “the results are important and should be helpful for physicians who manage high-risk patients with hypertension, particularly older individuals.” The study found that the benefits of intensive blood pressure therapy are likely to substantially outweigh serious adverse events in high-risk patients 75 or older, a group among which doctors are sometimes fearful of prescribing intensive treatment.
Phillips’ team included three Methodist colleagues and heart specialists at Yale-New Haven Health System and the Long Island Jewish Medical Center.
Currently, only half of Americans with high blood pressure have it under control, according to the AHA. Before the issuance of the new guidelines, the upper threshold for systolic high blood pressure had been 140 since 1993.