Comparison of blood pressure measurements on the bare and sleeved arms - what does it uncover?

Accurate office blood pressure (BP) measurement remains crucial in diagnosing and managing hypertension. In this study, we aimed to compare BP measurements done over a bare arm versus a sleeved arm, while controlling all other possible sources of variance. We collected BP measurements of 100 hypertensive patients visiting a nephrology and hypertension clinic between January 2019 and December 2023. Measurements were taken by a single operator and according to the updated guidelines. BP measurements were performed first with one arm bare, and the other arm sleeved, with measurements taken simultaneously. Then, measurements were again taken simultaneously after exposing the arm which was first sleeved, and dressing the arm which was bare at first. A nonparametric Wilcoxon test was performed to compare each patient's measurements on each arm. No statistically significant differences were found between the sleeved and the bare arm measurements, with one exception of SBP measured on the left arm (slightly lower SBP on the bare arm). While looking at the absolute value of differences, the median difference was impressive with a 7-8 mmHg systolic difference and 5.5 mmHg diastolic difference. Our study revealed a robust and unpredicted effect of clothing on BP; in some patients, BP was increased while in others decreased. Therefore, we believe there is importance in measuring BP on bare skin, regardless of clothing or sleeve type.