How to interpret “white coat hypertension” — when a person’s blood pressure reading is high at a doctor’s office but normal at home — has long been unclear.
Some research has suggested white coat hypertension is simply a reflection of the patient’s anxiety about visiting the doctor. Other studies have reported that it may be a precursor for the development of actual hypertension.
A major new study — a meta-analysis published earlier this week in the Annals of Internal Medicine — supports that second idea, that white coat hypertension may not be benign. It found that people with untreated white coat hypertension are twice as likely to die from heart disease as people with normal blood pressure.
The study’s authors say their findings suggest that patients and doctors should take white coat hypertension more seriously.
“Our findings support the pressing need for increased out-of-office blood pressure monitoring nationwide, as it’s critical in the diagnosis and management of hypertension,” said Dr. Jordana Cohen, the study’s lead author and an assistant professor at the University of Pennsylvania Perelman School of Medicine, in a released statement.
“Simultaneously, we advise individuals with untreated white coat hypertension to engage in lifestyle modifications, including smoking cessation, reduction in their alcohol intake, and making improvements to their diet and exercise regimens,” she added.
Hypertension is currently defined as having a “top” blood pressure reading of at least 130 or a “bottom” reading of at least 80. More than 100 million Americans — half of all adults — have the condition, according to the American Heart Association.
For the meta-analysis, Cohen and her colleagues reviewed the findings of 27 studies from around the world involving more than 60,000 patients. The patients ranged in age from 43 to 72 (median age: 56) and were followed for three to 19 years (median follow-up period: 8 years).
About 26,000 of the patients were found to have either white coat hypertension or a similar phenomenon known as “white coat effect” (when a patient being treated with medication for hypertension has elevated blood pressure readings in medical settings).
The analysis revealed that the patients with untreated white coat hypertension were 36 percent more likely to have heart disease and 109 percent more likely to die from a cardiac event, such as a heart attack, during the follow-up periods of the studies than those with normal blood pressure. They were also 33 percent more likely to die prematurely from any cause.
The analysis found no significant link, however, between white coat effect and an increased risk of early death. In other words, when people being treated for hypertension had higher blood pressure readings in their doctors’ offices than at home, they weren’t more likely to die of cardiovascular disease (or any other cause) than people with normal blood pressure.
Limitations and implications
This meta-analysis comes with several caveats. Most notably, all the reviewed studies were observational, which means they showed only an association between white coat hypertension and increased risk of heart disease and early death, not a direct cause-and-effect relationship.
Also, as an editorial that accompanies the study notes, the increased cardiovascular risk associated with white coat hypertension was found to be mostly present among older adults (those over the age of 55). Furthermore, the increased risk associated with white coat hypertension was significantly lower than that associated with sustained (at-home) high blood pressure readings.
Still, the authors of the editorial — Dr. Daichi Shimbo, a cardiologist at Columbia University, and Paul Muntner, an epidemiologist at the University of Alabama — believe the new study makes “an important contribution” to our understanding of the white coat hypertension phenomenon, particularly by underscoring the importance of monitoring of blood pressure at home.
“Out-of-office [blood pressure] monitoring is useful for distinguishing between [white coat hypertension] and sustained hypertension among person with high office [blood pressure],” they write.
“Studies suggest that about one in five adults may have white coat hypertension,” she says. “Our findings underscore the importance of identifying people with this condition. We believe individuals with isolated in-office hypertension — those who are not taking blood pressure medication — should be closely monitored for transition to sustained hypertension, or elevated blood pressure both at home and the doctor’s office.”
FMI: Abstracts of the meta-analysis and the editorial can be found at the Annals for Internal Medicine website. The full papers, however, are being a paywall, despite the fact that the study was funded in part by public money from the National Institutes of Health.