If you dread seeing the doctor and your blood pressure reading always seems to be high at the doctor’s office, a new review says you should take those elevated readings seriously.

The problem is called white-coat hypertension (because of doctors’ traditional white coats) and it may signal an underlying problem.

The research defined white-coat hypertension as elevated readings at the doctor’s office, along with normal blood pressure elsewhere. People who had untreated white-coat hypertension had double the risk of dying from heart disease or stroke compared with people with normal blood pressure.

The odds of having a heart attack or stroke were also about one-third higher for those with white-coat hypertension, according to the new review. Their risk of dying prematurely from any cause was also increased by about a third compared to people with no blood pressure problems.

“People with white-coat hypertension may not be monitored regularly. They may feel like nothing is wrong,” said lead author Dr. Jordana Cohen. She is an assistant professor at the University of Pennsylvania Perelman School of Medicine, in Philadelphia.

Cohen said everyone needs to know their blood pressure outside the doctor’s office. High blood pressure, or hypertension, is a defined as a top reading of at least 130 or a bottom one of 80. The condition affects nearly a third of American adults, the researchers said.

“Know what your blood pressure is, and what your goal is. Learn how to take blood pressure so you get a quality blood pressure reading. I think everyone should have a home monitor, even if their health care provider doesn’t specifically recommend it,” she said.

The study was published June 10 in the Annals of Internal Medicine.

Besides looking at white-coat hypertension, the review also looked at white-coat effect. This is when elevated in-office blood pressure is treated with medication. The concern is that if readings are only elevated in the doctor’s office, high blood pressure drugs might drop pressure too low.

But researchers didn’t find any significant links between white-coat effect and heart disease and strokes, or deaths from heart disease and strokes, or deaths from any cause.

The review included 27 previously completed studies. Those studies had nearly 26,000 people with white-coat hypertension or white-coat effect, and more than 38,000 with normal blood pressure. The studies went on for between three and 19 years.

Dr. Daichi Shimbo wrote an editorial that appeared in the same issue of the journal. It recommended adding out-of-office blood pressure readings to determine whether someone has white-coat hypertension, or sustained high blood pressure.

“This paper was extremely important. White-coat hypertension is perhaps, not benign,” he said.

“But if you have high office blood pressure, don’t you want to know whether or not the out-of-office blood pressure is high or not? If the out-of-office is high, then it’s sustained hypertension. This systematic review didn’t look at sustained hypertension,” Shimbo said.

And, he said, sustained high blood pressure is the real concern. Shimbo added that the people with white-coat hypertension who had the biggest risks were those who also had other risk factors, such as prior heart disease or chronic kidney disease.

Dr. Traci Marquis-Eydman is an associate professor at Netter School of Medicine at Quinnipiac University in Hamden, Conn. She agreed that the strongest risks appeared to be in people who had white-coat hypertension and other risk factors, such as an older age.

The review calls to mind the approach to diabetes management, she noted. “It’s important to individualize people’s treatment plans,” Marquis-Eydman said.

“This study shows it’s important to monitor blood pressure in more than one setting,” she explained.

All three experts said it’s important that blood pressure is taken properly — both in the office and out.

The American Heart Association advises avoiding caffeine, tobacco products and exercise for a half-hour before taking your blood pressure.

Empty your bladder, then sit quietly for at least five minutes before taking a reading. Sit with your back supported and your feet flat on the floor. Your arm should be supported on a table or other flat surface. Check the instructions on your monitor for proper placement of the cuff.

Cohen noted that your doctor may also order “ambulatory monitoring.” That means you wear a blood pressure cuff that takes measurements throughout the day and night.

More information

Here’s more on monitoring your blood pressure at home from the U.S. Department of Health and Human Services.