The unilateral measurement of blood pressure may mask the diagnosis or delay the effective treatment of hypertension.

Several studies have indicated the presence of significant interarm blood pressure (BP) differences; this could result in misclassification of BP status. Nevertheless, the findings of these studies were not consistent. This prospective, observational study investigated the presence and magnitude of interarm BP differences and determined the influence of age, gender, arm circumference, smoking, being hypertensive or diabetic, or having a previous history of cardiovascular disease in these differences. The study included 384 subjects, who were patients, ward visitors, and members of the nursing staff of this Department. BP measurements were recorded simultaneously in both arms by using 2 validated, fully automated oscillometric electronic devices. There were significant differences between the right arm and left arm systolic BP (p < 0.0005), between right arm and left arm diastolic BP (p < 0.05), and between right arm and left arm pulse pressure (p = 0.006). The mean interarm differences in systolic and diastolic BP measurements were 1.2 +/-5.0 mm Hg and 0.4 +/-4.2 mm Hg, respectively. There were 13 subjects (3.4%) and 4 subjects (1.04%) with an interarm systolic and diastolic BP difference of > 10 mm Hg, respectively, and a single patient with both interarm systolic and diastolic BP differences of > 10 mm Hg (0.26%). None of the studied demographic or clinical characteristics was a significant predictor of interarm systolic and diastolic BP differences. The authors conclude that significant interarm systolic and diastolic BP differences are frequently present. Therefore, the unilateral measurement of BP may mask the diagnosis or delay the effective treatment of hypertension. It is thus recommended that BP should be simultaneously measured in both arms at the initial consultation and the higher of the 2 readings should be used to guide further management decisions.