Taking blood pressure readings from both arms and using the higher reading would more accurately capture who has high blood pressure — and is at increased risk for cardiovascular disease and death — than relying on readings from a single arm, new research suggests.

While current recommendations call for using the higher arm reading, there was previously no evidence in the scientific literature to support the practice, which isn’t routinely followed, according to the study. The findings appeared this week in the American Heart Association journal Hypertension.

“If you are only doing one arm, you can’t know which is the higher-reading arm,” said lead study author Christopher Clark, a clinical senior lecturer in primary care at the University of Exeter Medical School in Devon, England. “And if you don’t catch high blood pressure, you can’t treat it. We can now support the adoption of using the higher reading from both arms.”

Nearly half of U.S. adults have high blood pressure, also known as hypertension. Blood pressure is considered high if the systolic reading, the top number, is 130 mmHg or more, or the diastolic reading, the bottom number, is 80 mmHg or more. High blood pressure is a risk factor for heart disease, heart attacks and strokes.

In a 2019 scientific statement detailing proper blood pressure measurement, the AHA recommended taking readings from both arms during an initial patient visit and using the arm with the higher reading for measurements at subsequent visits. The statement also called for making sure to use the proper cuff size based on the patient’s arm circumference, among other guidance.

In the new study, researchers analyzed medical data for 53,172 adults from 23 studies in countries around the world. Participants were an average of 60 years old.

They found using the lower arm’s reading, compared with the reading from the higher arm, resulted in 12% of people who had hypertension falling below thresholds for diagnosis or treatment of the condition.

Because hypertension also is used to help calculate a person’s risk for cardiovascular disease, missing a diagnosis of high blood pressure can have serious consequences, the authors noted.

According to the Centers for Disease Control and Prevention, high blood pressure was the primary or contributing cause of more than 670,000 deaths in the U.S. in 2020.