KeywordsInterarm blood pressure differences blood pressure monitoring cardiovascular disease aortic blood pressure A B S T R A C T Background: Inter-arm differences in brachial systolic Blood Pressure (BP) are associated with increased cardiovascular risk. It is unclear whether anatomical factors contribute to brachial Interarm Blood Pressure (IABP) differences or whether brachial IABP differences translate to differences in derived central aortic BP. This study aimed to ascertain whether IABP differences in brachial BP correlate with anatomical factors (arm side, dominance, and geometry) and translate to differences in derived central BP.Methods: Brachial BP and derived central BP were measured simultaneously in both arms in 77 community-dwelling adults (18-66 years, 38 male) using two SphygmoCor XCEL (AtCor Medical) BP devices. Measurements were taken 3-4 times in each participant, swapping devices between measurements. An optoelectronic volumeter (Perometer 350S) and hand-held dynamometer (Saehan) were used to measure arm volume and maximal hand-grip strength. Differences in brachial and derived central BP between arms were evaluated by paired t-tests. Regression analysis was used to examine predictors of IABP differences.Results: Absolute IABP difference in brachial systolic BP was 4.2 ± 3.6 mmHg. Brachial systolic IABP differences were not different between arms (right/left, dominant/non-dominant, or large/small arm volume). Brachial systolic IABP differences were not correlated with differences in arm volume or grip strength. Male sex and diastolic BP were the only predictors. Brachial systolic IABP difference translated to a small (3.1 ± 2.4 mmHg) difference in derived central BP. Conclusion:As there is only a single aortic BP, we consider the difference in derived central BP likely an artefact. The possibility that it results from BP variability warrants further investigation.