Reference: JAMA Intern Med. 2023 Aug 7 early online
Practice Point: Make sure the appropriate size blood pressure cuff is being used to avoid underdiagnosis and overtreatment of hypertension.
EBM Pearl: Crossover trials are trials in which participants serve as their own controls for 1 or more interventions (or assessments). The effects on all of the individuals are also compared to reach a final assessment of the effectiveness of the interventions being evaluated.
Scenario: The face sheet on the exam room door shows a blood pressure (BP) of 160/97 (taken by the nurse or MA). There are a few ways this can go from here. 1) You adjust the patient’s BP medications and move down the list of other problems. 2) You manually check the BP in the room and adjust treatment as necessary. 3) You conduct the visit per usual, and ask the nurse to recheck the BP at the end of the visit (assuming the elevated reading was from the hurried arrival and rooming process), and adjust the meds if needed. But because the person initially taking the BP is often not the person treating the BP, considerations related to how the BP is taken (such as cuff size) may not be getting the deserved attention. Well, a new crossover trial (Cuff(SZ) trial) published in JAMA strongly suggests that cuff size deserves your attention.
Previous studies evaluating the effect of cuff size on blood pressure readings were done with manual measurements and on specialized patient populations. However, we know that BP readings are affected by how blood pressure is taken (higher with manual than automated) and who is taking it (higher with doctors/APPs than nurses/MAs). The authors of this trial evaluated the effect of using a “regular” adult size BP cuff regardless of arm size when measured with an automated BP device in 195 community-dwelling adults (34% male, 68% Black, 51% with hypertension) with a wide range of arm circumferences. Investigators randomly assigned the order in which BP measurements were taken with too small, too large, or appropriate-sized cuffs (at least one of which was regular size), ending with a fourth measurement using the appropriate size cuff. Measurements were based on the average of triplicate readings.
The cuff-discrepancy in BP readings was most striking for those adults who needed an extra-large cuff (2 sizes bigger than regular) but who got measured using a regular cuff: the regular size cuff overestimated blood pressure by a mean 19.5/7.4 mmHg. A cuff just one size too large overestimated BP by a mean 4.8/1.8 mmHg. For those for whom the regular cuff was one size too big, the measurements with the regular size cuff underestimated the blood pressure by a mean -3.6/-1.3 mmHg.
Let’s go back to the scenario at the top. A BP reading 20/7 mmHg above goal according to JNC8 (or 30/17 mmHg above goal if you follow AHA/ACC) is not something a provider typically brushes off. In today’s busy practices, that BP is getting treated (and we do mean BP here rather than patient). And that’s a problem. So, next time you are in clinic, do your practice a favor and check to see whether your automated BP machines even have multiple sizes of cuffs in the cart, and make sure your staff are using them. And then, if the BP reading is high, consider checking it again. As they say in carpentry: measure twice, cut once. Or in this case, cuff once.
For more information, see the topic Blood Pressure Measurement and Monitoring in DynaMed.
DynaMed EBM Focus Editorial Team
This EBM Focus was written by Katharine DeGeorge, MD, MS, Senior Deputy Editor at DynaMed and Associate Professor of Family Medicine at the University of Virginia. Edited by Alan Ehrlich, MD, Executive Editor at DynaMed and Associate Professor in Family Medicine at the University of Massachusetts Medical School; Dan Randall, MD, Deputy Editor at DynaMed; Nicole Jensen, MD, Family Physician at WholeHealth Medical; Vincent Lemaitre, PhD, Medical Editor at DynaMed; Elham Razmpoosh, PhD, Postdoctoral fellow at McMaster University; and Sarah Hill, MSc, Senior Associate Editor at DynaMed.