The following originally appeared on The Upshot (copyright 2017, The New York Times Company).
In the week before Thanksgiving, the American Heart Association and the American College of Cardiology released new guidelines for the diagnosis and management of high blood pressure. This, probably more than anything else, made my blood pressure go up over the holiday.
The problem was not the guideline itself but some of the news coverage it prompted, with pronouncements that millions more Americans would need to lower blood pressure or that nearly half of Americans now had high blood pressure. A lot of the coverage made it sound as if something drastic had happened overnight.
Nothing had. We just changed the definition of hypertension.
High blood pressure, in general, is not something we should ignore. It’s a major risk factor for heart disease, second perhaps only to smoking, and people with hypertension often need to make changes to reduce their risk of a heart attack or stroke. But, as is so often the case with medical news, matters are more complicated than the headlines or TV summaries.
The new data that led to this guideline revision came from the Sprint study, a large randomized controlled trial of blood pressure management that was published in The New England Journal of Medicine in 2015. More than 9,300 patients were put into one of two groups.
The first received standard care, which involved trying to keep systolic blood pressure (the higher of the two blood pressure measures) under 140. The second group got more intensive care, which meant trying to keep systolic blood pressure below 120. Achieving the latter, of course, required more therapy, mostly pharmacologic in nature.
The results were significant, with fewer patients in the intensive therapy group having an acute cardiovascular event or death. The evidence was so compelling that the trial was stopped early, so the results could be announced sooner rather than later. This decision itself brought a fair amount of media attention to its findings. The fact that those in the intensive therapy group also had more adverse events, like hypotension, syncope and acute kidney injury, got less attention.
Regardless, this is a significant trial, and we should treat it seriously. To generalize its results, however, we have to pay attention to the details of its methods. To be eligible for this study, in addition to having a systolic blood pressure from 130 to 180, patients had to be at particularly high risk of disease. They had to be at least 50 years old. They had to have one of the following health problems: another subclinical cardiovascular disease, chronic kidney disease or a Framingham 10-year risk of cardiovascular disease of 15 percent or more. Or they had to be 75 years or older.
They also had to have their blood pressure confirmed in three separate readingsin which patients were left alone in a room for five minutes. This is important, because patients often have elevated blood pressure just from being nervous when it’s being measured in the office. There’s even a name for it: white coat hypertension.
Because of white coat hypertension, guidelines for checking blood pressure in both children and adults recommend that after multiple readings in the office, worrisome findings should be confirmed by 24-hour measurement outside the office. This happens far too rarely. Instead, people get their blood pressure measured quickly in the office, are labeled hypertensive, and are then put on treatment pathways.
The Sprint study essentially showed that people truly at high risk should have their blood pressure managed more aggressively than we thought. But that has not been the message of news on the new guidelines. That has focused far more often on the many newly reclassified people with mild blood pressure, who were not the focus of the Sprint intervention.
In fact, almost none of the newly labeled hypertensive people (those with systolic blood pressure between 130 and 140) should be placed on medications. These people should be advised to eat right, exercise, drink responsibly, and not smoke.
That’s exactly what physicians would have been advising people before these changes. Is there anyone left who doesn’t know those things are important for good health?
So why alter the guideline at all? The conclusion of an accompanying articleargues that the guideline “has the potential to increase hypertension awareness, encourage lifestyle modification and focus antihypertensive medication initiation and intensification on U.S. adults with high” cardiovascular disease risk. In other words, much of the goal is to make news and potentially scare people into changing their behavior.
Unfortunately, this is a tactic that has not been shown to work, at least not for all diseases. A 2015 meta-analysis in the journal Psychological Bulletin looked at all the research on fear messaging. The authors found that fear appeals could change attitudes, intentions and behaviors, but mostly on issues with a high susceptibility and severity. With respect to hypertension, it’s hard to believe we’re not already oversaturated with worry.
Fear messaging also works better when it’s intended to change one-time-only behaviors, not lifestyle or long-term activities. Most “new” people with high blood pressure should focus on how they live. The truth, unfortunately, is that it’s just easier to put people on medication than try to get them to modify their long-term behavior.
More people will probably be prescribed drugs because they’ve been told to be afraid and because they can’t get their blood pressure low enough with diet and exercise.
The potential upside from this change is that because of “awareness,” more people might make lifestyle changes that lead to lower cardiovascular risk in the future. The potential downside is that more people may receive a diagnosis of high blood pressure, be overtreated with medication, and endure side effects or adverse outcomes. It’s not irrational to fear that these new guidelines might lead to more of the latter than the former.
