Daily Dose: Effects of Cuff Size on Accuracy of BP Readings

Patient Care brings primary care clinicians a lot of medical news every day—it’s easy to miss an important study. The Daily Dose provides a concise summary of one of the website's leading stories you may not have seen.

Last week, we reported on a study published in JAMA Internal Medicine that examined the effects of “overcuffing” and “undercuffing” vs appropriate cuffing and to describe the effects of cuffing errors on blood pressure (BP) reading across multiple cuff sizes.

The study

Researchers recruited 195 participants with screening events at a public food market and a senior housing facility, and through mailings to prior study participants and study brochures in hypertension (HTN) clinics at Johns Hopkins University. Mean participant age was 54 years; 34% were men and 68% self-identified as Black. Approximately half (51%) had HTN, 20% had diabetes, and mean BMI was 28.8. Small, regular, large, and extra-large cuffs were appropriate for 35, 54, 66, and 40 participants, respectively.

Participants had their BP measured 3 times with each of the 4 cuff sizes in random order with 30 seconds between each of the 3 readings. The fourth measurement was taken with an appropriately sized cuff. All participants had their BP taken with the "regular" sized cuff at least once. Measurements were taken between 9 am and 6 pm and all participants followed the same protocol: Bladders were empty; they took a 2-minute walk before each set of measurements followed by 5 minutes of rest.

The findings

According to the results, for study participants who needed a large or extra-large cuff size, the use of a regular size cuff resulted in 4.8-mm Hg and 19.5-mm Hg higher systolic BP (SBP) readings, respectively, than with an appropriate size cuff (both P<.001). On the other hand, for participants who should have been using a small cuff, the result of using a regular size cuff was a SBP reading 3.6 mm lower (P<.001).

Readings for diastolic BP (DBP) also were consistently inaccurate for participants who used cuffs that were 1 size too large (-1.3 mm Hg); 1 size too small (1.8 mm Hg); and 2 sizes too small (7.4 mm Hg) (P<.001 for both small sizes).

Authors' commentary

"In this randomized crossover trial, miscuffing resulted in strikingly inaccurate BP measurements. This is particularly concerning for settings where 1 regular BP cuff size is routinely used in all individuals, regardless of arm size. A renewed emphasis on individualized BP cuff selection is warranted."

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