Invited Commentary
August 7, 2023
There Is No 1-Size-Fits-All to Blood Pressure Measurement—Cuff Size Matters
Mathias Lalika, Stephen P. Juraschek, LaPrincess C. Brewer
JAMA Intern Med. Published online August 7, 2023. doi:10.1001/jamainternmed.2023.3277
In this issue of JAMA Internal Medicine, Ishigami and colleagues1 reported a randomized crossover trial quantifying the effect of miscuffing on blood pressure (BP) measurement when using automated devices. The authors found that regular BP cuff size resulted in starkly inaccurate systolic and diastolic BP readings compared with an appropriately sized cuff, irrespective of arm size. The misestimation of BP was persistent when too small or too large cuffs were used instead of the appropriately sized cuffs. Interestingly, the degree of underestimation or overestimation increased as the appropriate cuff size progressed from the regular to extra-large BP cuff. More importantly, the effect of miscuffing did not vary with BP or obesity status.
Effect of Inaccurate BP Readings
Blood pressure measurement is the primary strategy for managing hypertension and reducing the prevalence of cardiovascular disease (CVD), the leading cause of morbidity and mortality globally. This makes accurate measurement of BP crucial. Errors in BP measurement may be associated with the underdiagnosis of hypertension, which is then associated with underestimation of CVD risk, delays in treatment, and early onset of hypertension-associated complications.2 Conversely, overdiagnosing hypertension potentially exposes individuals to unnecessary adverse drug effects. Misdiagnosis of hypertension is also associated with psychosocial and financial harms that are associated with clinical testing and treatment for individuals and health systems.
Challenge of Limited Cuff Size Availability
Automated oscillometric BP monitors have minimized the need for human judgment when performing sequential BP-taking steps as they are independent of motor and perceptual skills (eg, gradual deflation of the cuff, auscultation), thus reducing the likelihood of human error and bias.2,3 However, appropriate cuff selection is a critical step to accurate BP measurement. Current American Heart Association guidelines recommend arm circumference measurement followed by selecting a cuff with a corresponding bladder length and width.4 These procedures, in addition to the recommended 5-minute rest before acquiring 3 BP readings 1 minute apart may be time-consuming for clinicians, which may be associated with potential oversight in selection of an appropriate cuff size. In addition, there is a limited variety of available BP cuff sizes. Studies have shown that inappropriate cuff size and shape are associated with inaccurate BP readings in manual sphygmomanometers.2,5 The rapid adoption of automated BP devices in inpatient and outpatient settings warrants assessment of the effect of cuff size on BP readings, strengthening the importance of the Ishigami et al1 study.
Individualized Cuffs and the Growing Need for Automated BP Devices
The finding that miscuffing led to inaccurate readings in automated BP devices is important and novel for multiple reasons. To our knowledge, this is the first randomized crossover trial to examine the effect of miscuffing on automated BP readings. This study is timely, considering that automated digital BP monitors are increasingly used in inpatient and outpatient settings, with clinical guidelines recommending these devices.6 These findings emphasize the need for increased availability of a wide variety of BP cuff sizes in clinics and hospitals. As more health care systems adopt remote monitoring through electronic medical records (EMRs), automated BP monitors, especially those capable of syncing with EMRs, are more likely to become ubiquitous in the near future.
The study by Ishigami et al1 is also timely because of the increasing use of home BP monitoring devices.7 A display screen of readings, automatic deflation, and an eliminated need for auscultation make automated BP monitors user-friendly; thus, patients are more likely to purchase them for self BP monitoring. Additionally, the integration of telemedicine in clinical care has accelerated during the COVID-19 pandemic.8 The study by Ishigami et al1 provides more evidence to incentivize the introduction of a wide range of BP cuff sizes to the market. Furthermore, diversity in cuff size may prevent a mismatch of cuffs with limbs (eg, thigh cuffs with upper arms) and reduce the need for devices using alternative BP measuring sites, such as the forearm or wrist, that are not validated by existing protocols.4
Previous studies have predominantly assessed BP misestimation in individuals with obesity or larger arms, albeit with manual sphygmomanometers.2,5 The study by Ishigami et al1 demonstrated not only similar findings among patients with obesity, but also those with relatively smaller-sized arms. The results provide more evidence supporting the use of individualized BP cuff sizes and clears a misconception that the selection of appropriately sized cuffs is dichotomized to “normal” and larger-sized arms. Moreover, larger arms also vary in size. Another strength of this study is its diverse sample in terms of race and ethnicity, age, and sex.
This study by Ishigami et al1 has noteworthy limitations. The small sample size in subgroup analyses (participants with hypertension and obesity) may limit the interpretation of findings for these groups. In addition, the study did not consider arm shape, which is known to affect BP readings.5 Nonetheless, this study adds valuable evidence to inform the development and validation of automated BP devices.
Conclusions
These findings are especially relevant for underresourced clinics, such as federally qualified health centers, that are often not adequately equipped and instructed to measure BP correctly. Federally qualified health centers predominantly serve marginalized populations, such as racial and ethnic minority groups and socioeconomically disenfranchised individuals, who face CVD disparities. Thus, providing critical resources for the correct diagnosis of hypertension at the first point of contact with health care services for this population is a key strategy to achieving health equity. Considering the vital role of hypertension in addressing CVD, the US Centers for Medicare & Medicaid Services should consider incorporating arm circumference measurement and the availability of various cuff sizes as health equity metrics for health systems or payers.
The availability of various cuff sizes should be accompanied by the expansion of care teams to reduce the time burden on clinicians. Interventions integrating community health workers in care teams have shown promise in improving hypertension self-management among medically underserved populations.9,10 The reduced time constraints for clinicians will allow sufficient time for arm circumference measurement and correct cuff size selection.
The findings by Ishigami and colleagues1 also support the need for further development of technological tools to ensure the selection of appropriate cuff sizes. Digital technologies, such as wearables, mobile applications, and artificial intelligence, can be leveraged to efficiently take arm measurements and determine the appropriate cuff size and shape. Wearables synchronized with EMRs can provide clinicians with an up-to-date cuff size for patients before their visit, maximizing clinician time with patients. Similarly, these findings can inform the training of cuff-embedded artificial intelligence models capable of detecting inappropriately sized cuffs on arm fitting and prompting the clinician to select a correct cuff.
As the global burden of CVD rises, the accurate measurement of BP is extremely important. The US Food and Drug Administration should consider stipulating that validated automated BP monitors contain more specific information regarding the appropriate arm circumference size for the accompanying cuffs. Responsible agencies should also consider incentivizing manufacturers to encourage the development of more varieties in cuff sizes. With time, the availability of diverse BP cuffs and enforcement of clinical guidelines mandating arm circumference measurement when measuring BP will improve classification of hypertension status and quality of care.
