Prevalence and clinical implications of the inter-arm blood pressure difference: a systematic review

Abstract

A blood pressure (BP) difference between arms was first reported over 100 years ago. Knowledge of its prevalence and relevance to the accurate measurement of BP remains poor. Current hypertension guidelines do not emphasise it. The objectives of this study were to establish the best estimate of prevalence of the interarm difference (IAD) in the population, to consider its implications for accurate BP measurement and treatment, and to discuss its aetiology and potential as a risk marker for cardiovascular disease. Systematic literature review was carried out. The data sources were Medline EMBASE and CINAHL databases, and Index of Theses. Studies reporting prevalence rates of IAD were retrieved and considered for inclusion against explicit methodological criteria. Point prevalence rates were extracted and weighted mean prevalence rates calculated. The main outcome measures were weighted mean prevalences of systolic IADX10 and X20 mm Hg and of diastolic IADX10 mm Hg. Thirty-one studies were identified. Most had methodological weaknesses; only four met the inclusion criteria. Pooled prevalences of the IAD from these four studies were 19.6% systolic X10 mm Hg (95% CI 18.0-21.3%), 4.2% systolic X20 mm Hg (95% CI 3.4-5.1%) and 8.1% diastolic X10 mm Hg (95%CI 6.9-9.2%). In conclusion, an IAD is present in a substantial number of patients and should be looked for whenever diagnosis and treatment depend on accurate measurements of BP. The importance of an IAD should be better emphasised in current hypertension management guidelines. There is evidence associating an IAD with peripheral vascular disease, raising the possibility that its presence may predict cardiovascular events. IntroductionPatients are regularly encountered in the clinical setting with a different systolic or diastolic blood pressure (BP) in each arm. Comparisons of arm pressures have been made ever since the modern sphygmomanometer was introduced, 1 yet the significance of this finding, which Cyriax named the 'differential BP sign', 2 is still poorly appreciated today.Hypertension is one of the major causes of premature morbidity and mortality throughout the developed and developing worlds. 3 The vast majority of patients with hypertension are managed in primary care 4 and measurement of BP is the most common investigation performed in this setting. 5 The management of hypertension is known to be suboptimal; 6 therefore, knowledge of the latest guidelines, and the many factors known to influence readings, is crucial. 7 The prevalence of a systolic (sIAD) or a diastolic (dIAD) inter-arm difference, its importance for the management of hypertension, its significance as a potential marker of peripheral vascular disease (PVD) and predictor of cardiovascular disease (CVD) in hypertensive patients are the subjects of this review.Although recent ambulatory BP monitoring guidelines recommend routine bilateral assessment, 8 the latest British guidelines for the management of hypertension merely state that 'BP should initially be measured in both arms as patient...

The interarm blood pressure difference as predictor of cardiovascular events in patients with hypertension in primary care: cohort study

“…The sequential method of BP recording was chosen as a pragmatic method of investigation within the consultation; we have addressed the limitations of this method elsewhere. 4 However, the small difference in the magnitude of the absolute BPs between the right and left arms suggests that no systematic bias was introduced by this method, and this is in keeping with data from previously reported large series. 7,[20][21][22] Although there was good correlation of IADs between attendances, this study did not measure changes to the IAD over the follow-up period.…”

“…Although our prevalence figures of 23% with a sIAD X10 mm Hg and 6% with a dIAD X10 mm Hg are lower than the figures that we and others have reported previously from primary care, 3,7,15,16 they are close to the best estimates we have calculated from the most methodologically robust studies. 4 We had anticipated a higher prevalence of the IAD than we reported previously, as it has been shown to occur more frequently in hypertensive than normotensive populations in selective studies, 4,[17][18][19] but no previous series of hypertensive patients reported from primary care was available to support this contention. The final prevalence figures were lower than those in our interim report 3 on this cohort, but we have previously shown that prevalence will fall with repeated pairs of measurements.…”

“…4 Current guidelines for the management of hypertension do not recognise these prevalences and refer only to checking for an IAD in the initial assessment of patients. 5,6 Appreciation of the presence of an IAD clearly is vital for the accurate diagnosis and consistent management of hypertension.…”

Association between Systolic Blood Pressure Difference ≥10 mm Hg and Ankle-Brachial Index

“…Some studies reported that an increased carotid-the intima-media thickness (IMT) in the left carotid artery [15] [16]. A previous study suggested that the cause of |ΔSBP| ≥10 mm Hg was pathologic rather than physiologic [17]. In addition to anatomical evidence for |ΔSBP| ≥10 mm Hg, aortic dissections, aortitis, infraclavicular arterial occlusion, and arterial embolism may be attributed to a thrombus complicated by atrial fibrillation, congenital coarctation of the aorta, or higher BP in the left arm, compared with the right arm [18] [19].…”

Authors' response

“…It seems ludicrous at a time when GPs in particular are being asked to provide more and more evidence of their fitness to work as GPs in the form of extended training, changes to examinations, and reaccreditation, that there is a group of nurses working in the NHS doing very similar work, with similar outcomes, and patient satisfaction, 2 with nothing more mandatory than a registered nurse qualification.…”