Despite clinical guidelines recommending the individualized selection of blood pressure cuff size, a regular adult cuff is often used. Researchers conducted a randomized crossover trial to determine the effect on automated blood pressure readings of using a regular adult blood pressure cuff instead of a cuff sized for a person's measured midarm circumference.

A total of 195 community-dwelling adults underwent four sets of triplicate blood pressure measurements. The initial three sets used an appropriate, too small, or too large cuff (based on measured arm circumference) in random order, whereas the fourth set repeated measurements taken using the appropriately sized cuff.

Among people requiring a small cuff, use of a regular cuff resulted in a significantly lower systolic blood pressure reading, with a mean difference of -3.6 mmHg. By contrast, among people requiring a large cuff, use of a regular cuff resulted in a significantly higher systolic blood pressure reading, with a mean difference of 4.8 mmHg. For those requiring an extra-large cuff, the mean systolic blood pressure reading using a regular cuff was 19.5 mmHg higher. These findings were consistent, although to a lesser extent, for diastolic blood pressure.

Use of appropriately sized cuffs is critical to avoiding the over- and underdiagnosis of hypertension, the authors conclude.

The authors note that the study has several limitations, including the small sample size of some subgroups, which was insufficient for analysis. In addition, the magnitude and direction of blood pressure differences were heterogeneous across individuals, and blood pressure was measured by trained staff using a rigorous protocol, so the degree of bias due to miscuffing could be more significant in a real-world setting.