Arm Size Coverage of Popular Over-the-Counter Blood Pressure Devices and Implications in US Adults

Hypertension is the leading cause of cardiovascular disease and premature death worldwide.¹ An accurate blood pressure (BP) measurement is essential for the diagnosis and treatment of hypertension; however, crucial steps to obtain accurate measurements (eg, patient positioning) are often not fully taken due to time and resource constraints. In this context, a recent trial clearly demonstrated the considerable impact of cuff size on BP reading.² Specifically, a cuff that is 1 size too small or 1 size too large can respectively overestimate or underestimate BP reading by ≈5 to 10 mm Hg. According to recent data from the National Health and Nutrition Examination Survey, about half of US adults require a large (appropriate for mid-arm circumference >34 to ≤44 cm) or extra-large (>44 cm) cuff size.³ However, cuff sizing and availability can vary across different BP devices or manufacturers.⁴ An important knowledge gap in this context is the limited investigation on the availability of cuff sizes in popular home BP devices in online retailers, while experts emphasize the potential importance of home BP monitoring in hypertension management.⁵ Thus, we evaluated the cuff sizes in 10 popular BP devices from a large online retailer and quantified the coverage of arm circumference ranges in US adults.

We searched Amazon’s Automatic Blood Pressure Category for popular home BP devices on January 3, 2024. We ensured the identification of the most widely used devices by referring to the device ranking, number of purchases, and number of ratings in the past month. Our goal was to procure at least 10 devices. Considering the possibility of needing to exclude some devices due to their specifications or unavailability, we aimed to purchase 16 devices. Indeed, 6 devices were unavailable for purchase. We recorded appropriate arm sizes for each device listed on the Amazon webpage, device manual, and cuffs. Although either or both inches and centimeters were used across devices, we standardized all measurements to centimeters for the present study (1 inch=2.54 cm). Although several manufacturers provide optional cuff sizes at extra cost, this project focused on the cuff sizes that come with BP devices since most consumers are likely to use those default cuffs. Subsequently, we quantified the number of US adults who would not be eligible to use those popular devices due to arm circumference, utilizing data from the National Health and Nutrition Examination Survey 2015 to 2020. We included 13 826 adults (≥18 years) without concurrent pregnancy and missing information on arm circumference (mean age of 47 years, with 51% women). Hypertension was defined as BP ≥130/80 mm Hg or self-reported physician diagnosis of hypertension (including individuals on antihypertension medication).

Of the 10 devices, 9 offered cuff sizes covering arm circumferences from 22 to 42 cm (1 device with 2 cuff sizes) and 1 from 22 to 40 cm (Table). Based on data from the National Health and Nutrition Examination Survey 2015 to 2020, 6.7% of US adults (corresponding to 17.3 million adults based on the 2023 US census) could not use these devices as is since their arm circumferences were <22 cm (0.3% [0.8 million], including 32.3% with hypertension) or >42 cm (6.4% [16.5 million], including 67.3% with hypertension). The proportion of adults not covered by these devices was higher in Black adults (11.8%) than in other racial/ethnic groups (White adults [6.6%], Hispanic adults [5.2%], and Asian adults [1.8%]; P value across race/ethnicity <0.001). The proportions of women (6.9%) and men (6.6)% not eligible for these devices were similar (P value across sex=0.731).

Our study found that, based on the standard cuff size provided, most of the popular devices in a larger online retailer accommodate an arm circumference of 22 to 42 cm. This indicates that 6.7% of US adults are not eligible to use these devices as is. While seemingly a small proportion of the population, this corresponds to ≈17 million adults in the United States. Of importance, Black adults are most affected by this issue; 1 in 8 Black adults is not eligible for these popular devices without an extra optional cuff—higher than any other race or ethnicity. This disparity is particularly concerning given the already high and increasing prevalence of hypertension in the Black population. To increase equity, manufacturers should prioritize the development and affordable sale of BP measuring devices that accommodate arm circumferences >42 cm. For example, with the same 20-cm interval of coverage, a device able to cover an arm circumference of 25 to 45 cm (instead of 22–42 cm) could accommodate 2.3 million more US adults. In this context, we should acknowledge a recent study reporting the overestimation of BP using this type of wide range or universal cuff (eg, 22–42 cm) in individuals with a larger arm circumference (>32–42 versus 22–32 cm).⁶ Nonetheless, retailers should allow customers to filter BP devices based on their specific arm circumferences and also ensure that any optional cuff sizes are clearly stated on webpages. Ideally, consumers should be able to select their appropriate cuff size without extra cost. Furthermore, health care providers should instruct patients about the importance of selecting an appropriate cuff size when purchasing a home BP device. A few limitations of this study are our limited exploration of a single (although the second largest) retailer and 10 devices. Despite the emphasis on the importance of home BP monitoring, ≈20 million US adults may not be eligible to use popular BP devices without purchasing an optional cuff due to their arm circumference, and Black adults are more susceptible to this issue than other racial/ethnic groups. Addressing this unrecognized disparity in device design is crucial for quality and equitable hypertension diagnosis and management integrating home BP monitoring.