Clinicians who do not correctly match blood pressure cuff size to their patients may arrive at inaccurate measurements and diagnoses, according to new research to be presented this week at an American Heart Association conference.

Investigators from Johns Hopkins University zeroed in on widely used automated blood pressure monitors and did not study manually inflated mercury sphygmomanometers. Participants underwent three sequential automated blood pressure measurements, 30 seconds apart. 

Underestimation of blood pressure when using a too-large cuff resulted in missed hypertension in 22% of patients, said study author Tammy M. Brady, M.D., Ph.D. And the problem was even more troubling in patients with obesity, who made up 40% of the 165 participants, she reported. Overestimation of blood pressure due to using a cuff that is too small misclassified 39% of participants as hypertensive.

“Accurate blood pressure measurement depends on proper patient preparation, positioning, measurement technique and individualized selection of cuff size, which should be based on the measured mid-arm circumference,” Brady said in a statement.

“It’s important for health care professionals and the public to recognize the importance of cuff size for the clinician’s office, kiosk and home blood pressure measurement,” she added. “For example, cuff size may be even more important in communities with high prevalence of obesity, since large or extra-large cuff sizes may provide more accurate blood pressure readings in those individuals,” she concluded.

High blood pressure increases the risk for multiple chronic and potentially deadly conditions including heart disease, stroke and kidney disease, according to the AHA.

The AHA’s Epidemiology, Prevention, Lifestyle & Cardiometabolic Health Conference 2022 takes place from March 1 through March 4.