The researchers compared standard arm cuff size ranges for popular retail automatic blood pressure measuring devices to arm circumference data from U.S. government-sponsored national health surveys.

Their analysis revealed that about 6.7 percent of U.S. adults — roughly 17.3 million individuals — have arms that wouldn’t fit standard cuff sizes. For the majority — 6.4 percent, an estimated 16.5 million U.S. adults — the cuffs would be too small. They also found that this problem disproportionately affects Black adults, nearly 12 percent of whom have arm circumferences outside the standard available cuff-size range.

Improper cuff fits can result in substantial errors in blood pressure readouts, and may simply prevent people from accurately monitoring their blood pressure at all.

The findings were published September 5 in the journal Hypertension, and will be presented September 6 at the American Heart Association’s annual Hypertension meeting in Chicago.

“The fact that millions of Americans are affected shows that this is not a small problem; and probably the easiest solution is for retailers just to offer a wider range of cuff sizes for no extra cost,” says study senior author Kunihiro Matsushita, MD, PhD, professor in the Bloomberg School’s Department of Epidemiology.

The study’s first author is Eileen Kaur, who was a high school intern in the Matsushita Laboratory at the time the research was conducted.

The authors also recommend that health care providers instruct patients about the importance of selecting proper cuff sizes when buying home blood pressure measuring devices.

Hypertension — typically defined as blood pressure consistently greater than 130/80 — is a driver of heart disease, stroke, kidney disease, vision problems, and dementia, and is considered a major cause of premature death worldwide. Treating hypertension properly requires accurate blood pressure measurement. Prior studies have shown poor fitting blood pressure device cuffs reduces measurement accuracy.

For their study, the research team identified 16 popular automatic blood pressure devices in early January 2024, based on reviews and sales in the past month. The team purchased 10 devices. (Several were not available; others were not arm cuffs.) The research team then compared device cuff sizes to a sample of arm circumference measurements among 13,826 American adults included in U.S. National Health and Nutrition Examination Surveys (NHANES) conducted from 2015 to 2020.

Nine devices included cuffs that covered a range of arm circumferences from 22 to 42 centimeters — 8.6 to 16.5 inches. One device cuff measured from 22 to 40 centimeters/8.6 to 15.7 inches. The NHANES data indicated that 6.7 percent of U.S. adults, corresponding to 17.3 million individuals based on 2023 U.S. Census numbers, have arm circumferences outside that range — 0.3 percent with arm circumferences below 22 centimeters/8.6 inches and 6.4 percent with arm circumferences above 42 centimeters/16.5 inches. The latter translates to an estimated 16.5 million U.S. adults.

The NHANES data, when broken out by race/ethnicity, suggested that 11.8 percent of Black adults, nearly double the national average, have arm sizes outside the standard range. This disparity is particularly concerning, Matsushita says, because Black adults have a significantly higher prevalence of hypertension than other major racial/ethnic groups: 57.1 percent versus 43.6 percent for white adults and 43.7 percent for Hispanic adults.

Some of the devices evaluated in the study did offer cuff sizes outside the standard range, but only as separate items that could be purchased at extra cost after buying the standard package. The researchers recommend that manufacturers of automatic blood pressure devices instead offer a selection of cuff sizes covering a wider range of arm circumferences.

“Consumers should be able to buy the blood pressure cuff sizes they need just as they can buy clothing sizes they need,” Matsushita says.

Even an upward shift of the existing 20 centimeter/8.6 inches range of cuff sizes, to 25 to 45 centimeters/9.8 to 17.7 inches, would result in greater coverage of American arm sizes, the researchers note.