Inter-arm blood pressure differences compared with ambulatory monitoring: a manifestation of the ‘white-coat’ effect?

Abstract

BackgroundInter-arm difference in blood pressure of >10 mmHg is associated with peripheral vascular disease, but it is unclear how much of the difference in sequential right and left arm blood pressure measurements might be due to a 'white-coat' effect. AimTo use ambulatory blood pressure monitoring (ABPM) to better understand the clinical significance of inter-arm differences in blood pressure. Design and settingRetrospective study in a teaching hospital in Birmingham. MethodAnonymised clinical data collected from 784 patients attending a single hospital-based hypertension clinic were retrospectively analysed. Each participant had blood pressure measured sequentially in both arms, followed by ABPM over the subsequent 24 hours. ResultsData were available for 710 (91%) patients, of whom 39.3% (279) had a blood pressure difference of 10 mmHg or more between each arm. Compared to daytime systolic ABPM, the difference was 25.1 mmHg using the arm with the highest reading, but only 15.5 mmHg if the lower reading was taken (mean difference 9.6 mmHg (95% confidence interval [CI] = 9.0 mmHg to 10.3 mmHg)). However, differences between mean right (20.7 mmHg) or left (19.9 mmHg) arm blood pressure and daytime systolic ABPM were very similar. ConclusionCompared with ABPM, use of the higher of the left and right arm readings measured sequentially appears to overestimate true mean blood pressure. As there is no significant difference in the extent of disparity with ABPM by left or right arm, this is unlikely to be due to arm dominance and may be due to the 'whitecoat' effect reducing blood pressure on repeated measurement. Where a large inter-arm blood pressure difference is detected with sequential measurement, healthcare professionals should re-measure the blood pressure in the original arm. KeywordsAmbulatory blood pressure; blood pressure monitoring; cardiovascular risk; white coat hypertension.

Difference in Blood Pressure between Arms of Normotensive Female Farmers in the Semi-arid Midlands of Kenya

“…Kim [19] observed that if the difference is 10 mmHg or more on repeated simultaneous measurements, the likelihood of peripheral vascular disease of the upper extremities is high and further diagnostic evaluation is warranted, especially in people with other risk factors for cardiovascular disease. Kim [19] also recommended that subsequent blood pressure monitoring should use the arm with the higher readings and these findings agree with those of Martin et al [18,19] who suggested that differences in right and left arm pressures may be caused by undiagnosed peripheral vascular disease affecting the upper limbs and may therefore predict an increased risk of cardiovascular disease.…”

“…It was first recognised more than 100 years ago [8]. Hence, 13 out of 15 blood pressure guidelines recommend that BP should be measured on both arms during initial clinical evaluation [16,17] and the arm with the higher BP be used at subsequent visits, but there is little evidence that this is followed [18]. Agarwal et al [13] have pointed out that BPs differ between arms, with the right arm consistently reading higher by a small amount.…”

Upper Extremity Blood Pressure Difference in Patients Undergoing Carotid Revascularisation

“…In sequential blood pressure measurement the so called 'white coat-effect' could contribute to the amount of blood pressure difference recorded, in which the first measurement is higher than the second. 16 However, our results showed an association between inter-arm blood pressure difference in SBP and subclavian stenosis, making it less likely that recorded differences were attributable to a 'white coat-effect'. Thirdly, the mean SBP in our subgroup of patients was much higher than the mean SBP in ICSS (165 mmHg vs 147 mmHg), indicating poor control of hypertension in our patients.…”

Inter-arm blood pressure difference and mortality: a cohort study in an asymptomatic primary care population at elevated cardiovascular risk

“…Sequential rather than simultaneous measurements are associated with two-to threefold higher prevalences, 11,22 and prevalence is over-estimated when measurements are not repeated, 10,11,23 due at least in part to white-coat effects. 23,24 Thus simultaneous, automated repeated measurements of IAD should be a reference standard for epidemiological study. 10 However, the authors have found that a single sequential pair of measurements can exclude confirmed IAD with a high negative predictive value, 11,12 and designed this study to investigate whether IADs detected by this simple method can also predict survival differences.…”