Doctors have long been puzzled by white coat hypertension (WCH), a condition that causes a person’s blood pressure reading to be high in a doctor’s office but normal at home. White coat hypertension used to be considered a result of the stress induced by doctor’s appointments.

Now, new research suggests that if white coat hypertension goes untreated, it could increase your chances of suffering from a cardiovascular event and dying from all causes. The new analysis was published yesterday in the Annals of Internal Medicine.

The authors of the new report, which was primarily funded by the National Institutes of Health, set out to better explain the effects of white coat hypertension, which has heretofore been very mysterious to the medical community. Prior to this new report, the long-term risks associated with white coat hypertension were “unclear,” the authors say.

Researchers looked at data from 27 separate studies. Compared with people who have normal blood pressure, those with white coat hypertension were twice as likely to die from a cardiac event. They also had a 33% increased risk of death from all causes and a 36% increased risk for cardiac events, such as heart attacks.

 

The authors say the evidence underscores the importance of recent guidelines recommending that people have their blood pressure checked outside of doctors’ offices to screen for hypertension.

It’s worth noting that older patients with white coat hypertension appear to be at greater risk than younger patients with the condition. Additionally, the risks were higher for patients who participated in studies that included at least a five-year follow-up. This indicates that risks associated with white coat hypertension increase with time.

An editorial accompanying the new study points out that the analysis doesn’t prove that white coat hypertension is the direct cause of increased risk of cardiovascular trouble. In addition to older patients, patients with a history of cardiovascular disease, and patients with diabetes or chronic kidney disease might be more likely to suffer from white coat hypertension, the editorial says. “The increased CVD risk associated with WCH may be present only among older persons who have high CVD risk,” the editorial says.

It calls for more research on the topic, saying, “Only 2 studies in the meta-analysis were conducted in the United States, and the applicability of these findings to non-Hispanic black and Hispanic adults in the United States is unknown.”

But the editorial, along with the study, notes the importance of blood pressure monitoring outside of doctors’ offices. Hypertension is the most preventable cause of premature mortality and disability worldwide, the study authors point out.