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Do differences in blood pressure between arms matter?
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Do differences in blood pressure between arms matter? Published Online January 30, 2012 DOI:10.1016/S01406736(11)61926-0
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In The Lancet, Christopher Clark and colleagues1 present data from a systematic review and meta-analysis assessing the available evidence linking differences in blood pressure between arms with both central and peripheral vascular disease. They establish that systolic differences of at least 15 mm Hg are associated with an increased risk of peripheral vascular disease (relative risk 2·5, 95% CI 1·6–3·8) and report weaker but significant associations with cerebrovascular disease and mortality. When subclavian stenoses are angiographically proven, Clark and co-workers estimate that the mean difference in blood pressure between arms is 36·9 mm Hg (95% CI 35·4–38·4), and rates of subclavian stenosis are high when differences are present. National and international hypertension guidelines have recommended measurement of blood pressure in both arms for some years, but the justification has been poor and subsequent adoption in primary care negligible.2–4 The main reason for these recommendations has been reduction of measurement error, although the European Society of Hypertension and European Society of Cardiology guidelines5 refer to differences between arms as a sign of peripheral vascular disease. Key issues are how to measure such differences, which measurement of blood pressure to use, and what to do when a difference is detected. Method of measurement is important because the prevalence of a difference more than doubles with
sequential measurement (one arm then the other) compared with simultaneous measurement of both arms with two sphygmomanometers or specialised machines.6 Preliminary data suggest that the significant differences recorded with sequential measurement are due to the so-called white-coat effect.7 Few family doctors will have two sphygmomanometers in their clinic rooms, but a spare model of the accurate digital monitors now in common use could easily be available.8 The alternative, historically, has been for measurement to depend on the side of the desk a patient sits and hence which arm is nearer to the physician. Clark and co-workers1 suggest that variation caused by method of measurement is no longer acceptable. In view of the association with vascular disease, guideline recommendations to use the highest blood pressure seem appropriate.2,3 No studies of peripheral vascular disease included a reference standard that used definitive diagnosis rather than reduced ankle-brachial pressure index. Therefore, although an asymptomatic difference might prompt checking of this index, no findings suggest what to do afterwards. Clark and colleagues’ data1 for increased cardiovascular mortality in the presence of a difference suggest that treatment with lipid-lowering and antiplatelet drugs could be indicated after detection of a difference, but such an approach has not been tested in randomised trials. However, not all studies in Clark and colleagues’ review1 used the simultaneous measurement method and most included patients known or thought to be at increased cardiovascular risk. Therefore, how useful bilateral measurements of blood pressure are in people with essential hypertension and no additional risk factors is unclear. Many studies in the review were cross-sectional, so whether differences in systolic blood pressure are predictive of future disease or a marker of existing disease is impossible to establish. Although the three cohort studies included in the review did show that differences in systolic blood pressure were associated with increased cardiovascular mortality, the effect size (hazard ratio 1·7, 95% CI 1·1–2·5) is of a magnitude that does not exclude the possibility of residual confounding.1 This report has several implications. First, the high specificity (96%) of the association between a difference in systolic blood pressure between arms of more than www.thelancet.com Vol 379 March 10, 2012
Comment
15 mm Hg and peripheral vascular disease justifies use of this measure as a sign of disease. Second, the low sensitivity (15%) shows that measurement of differences is of little value as a screening test for peripheral vascular disease, and ankle-brachial pressure indices will still be necessary for diagnosis. Third, the high prevalence of differences in some of the studies (eg, 7% of participants had an inter-arm difference of 15 mm Hg or higher in one community-dwelling cohort)9 suggests that many people with hypertension will be missed when blood pressure is measured in only one arm. Further research is needed to clarify whether substantial differences between arms should prompt aggressive management of cardiovascular risk factors. Overall, Clark and colleagues’ systematic review and meta-analysis1 supports existing guidelines stating that blood pressure should be measured in both arms. Ascertainment of differences should become part of routine care, as opposed to a guideline recommendation that is mostly ignored.
We declare that we have no conflicts of interest. 1
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Clark CE, Taylor RS, Shore AC, Ukoumunne OC, Campbell JL. Association of a difference in systolic blood pressure between arms with vascular disease and mortality: a systematic review and meta-analysis. Lancet 2012; published online Jan 30. DOI:10.1016/S0140-6736(11)61710-8. Krause T, Lovibond K, Caulfield M, McCormack T, Williams B. Management of hypertension: summary of NICE guidance. BMJ 2011; published online Aug 25. DOI:10.1136/bmj.d4891. Chobanian AV, Bakris GL, Black HR, et al. The seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure: the JNC 7 report. JAMA 2003; 289: 2560–72. Heneghan C, Perera R, Mant D, Glasziou P. Hypertension guideline recommendations in general practice: awareness, agreement, adoption, and adherence. Br J Gen Pract 2007; 57: 948–52. Mancia G, De Backer G, Dominiczak A, et al. 2007 ESH-ESC guidelines for the management of arterial hypertension: the task force for the management of arterial hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC). Blood Press 2007; 16: 135–232. Verberk WJ, Kessels AG, Thien T. Blood pressure measurement method and inter-arm differences: a meta-analysis. Am J Hypertens 2011; 24: 1201–08. Martin U, Holder R, McManus RJ. Right and left arm blood pressure variability: a manifestation of “white coat” effect? British Hypertension Society Annual Scientific meeting; Cambridge, UK; Sept 14–16, 2009: S15. A’Court C, Stevens R, Sanders S, Ward A, McManus R, Heneghan C. Type and accuracy of sphygmomanometers in primary care: a cross-sectional observational study. Br J Gen Pract 2011; 61: e598–e603. Aboyans V, Criqui MH, McDermott MM, et al. The vital prognosis of subclavian stenosis. J Am Coll Cardiol 2007; 49: 1540–45.
*Richard J McManus, Jonathan Mant Department of Primary Care Health Sciences, University of Oxford, Oxford OX1 2ET, UK (RJM); and Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK (JM) [email protected]
Family matters: sexual dimorphism in cardiovascular disease Early identification and management of disease risk is essential to sustain health and quality of life. Several algorithms have been developed to calculate an individual’s risk of coronary heart disease, including the Framingham and the Reynolds risk scores, but these have restricted use in identification of risk for both men and women. Sex-specific determination of risk is crucial in view of the validated sexual dimorphism in incidence, age of onset, progression, treatment efficacy, and morbidity and mortality for coronary artery disease.1–8 The two risk scores share several features. Both algorithms stratify by age, sex, systolic blood pressure, HDL cholesterol, and present smoking status. However, they differ in several important aspects. Whereas the Framingham risk score includes use of drugs for hypertension, the Reynolds risk score includes a measure of inflammation (high-sensitivity C-reactive protein [hs-CRP]) and family history of heart attack before age 60 years—ie, for the Reynolds risk score, your family matters. So what are the inherited genotypes that www.thelancet.com Vol 379 March 10, 2012
affect cardiovascular risk for the individual? Although the Reynolds risk score might slightly improve risk prediction for women compared with the Framingham risk score, can the algorithms be improved to better predict risk for both men and women? In The Lancet, Fadi Charchar and colleagues9 provide insight into genetic variants and potential new approaches to understanding of inheritable coronary artery disease in men. The Y sex chromosome is transmitted from father to son. Genes on the haploid portion (the male-specific region) of the Y chromosome are needed for development of the testes and affect development of hypertension as well as total and LDL cholesterol.10,11 Using material available from more than 3000 unrelated men participating in two large studies in the UK (the cross-sectional British Heart Foundation Family Heart Study, and the prospective West of Scotland Coronary Prevention Study), these investigators identified two haplogroups that accounted for 90% of the variation
Published Online February 9, 2012 DOI:10.1016/S01406736(12)60200-1 See Articles page 915 For more on the Framingham risk score see http://mdcalc. com/framingham-coronaryheart-disease-risk-score-si-units/ For more on the Reynolds risk score see http://www. reynoldsriskscore.org
873
Do differences in blood pressure between arms matter? Published Online January 30, 2012 DOI:10.1016/S01406736(11)61926-0
Science Photo Library
See Articles page 905
872
In The Lancet, Christopher Clark and colleagues1 present data from a systematic review and meta-analysis assessing the available evidence linking differences in blood pressure between arms with both central and peripheral vascular disease. They establish that systolic differences of at least 15 mm Hg are associated with an increased risk of peripheral vascular disease (relative risk 2·5, 95% CI 1·6–3·8) and report weaker but significant associations with cerebrovascular disease and mortality. When subclavian stenoses are angiographically proven, Clark and co-workers estimate that the mean difference in blood pressure between arms is 36·9 mm Hg (95% CI 35·4–38·4), and rates of subclavian stenosis are high when differences are present. National and international hypertension guidelines have recommended measurement of blood pressure in both arms for some years, but the justification has been poor and subsequent adoption in primary care negligible.2–4 The main reason for these recommendations has been reduction of measurement error, although the European Society of Hypertension and European Society of Cardiology guidelines5 refer to differences between arms as a sign of peripheral vascular disease. Key issues are how to measure such differences, which measurement of blood pressure to use, and what to do when a difference is detected. Method of measurement is important because the prevalence of a difference more than doubles with
sequential measurement (one arm then the other) compared with simultaneous measurement of both arms with two sphygmomanometers or specialised machines.6 Preliminary data suggest that the significant differences recorded with sequential measurement are due to the so-called white-coat effect.7 Few family doctors will have two sphygmomanometers in their clinic rooms, but a spare model of the accurate digital monitors now in common use could easily be available.8 The alternative, historically, has been for measurement to depend on the side of the desk a patient sits and hence which arm is nearer to the physician. Clark and co-workers1 suggest that variation caused by method of measurement is no longer acceptable. In view of the association with vascular disease, guideline recommendations to use the highest blood pressure seem appropriate.2,3 No studies of peripheral vascular disease included a reference standard that used definitive diagnosis rather than reduced ankle-brachial pressure index. Therefore, although an asymptomatic difference might prompt checking of this index, no findings suggest what to do afterwards. Clark and colleagues’ data1 for increased cardiovascular mortality in the presence of a difference suggest that treatment with lipid-lowering and antiplatelet drugs could be indicated after detection of a difference, but such an approach has not been tested in randomised trials. However, not all studies in Clark and colleagues’ review1 used the simultaneous measurement method and most included patients known or thought to be at increased cardiovascular risk. Therefore, how useful bilateral measurements of blood pressure are in people with essential hypertension and no additional risk factors is unclear. Many studies in the review were cross-sectional, so whether differences in systolic blood pressure are predictive of future disease or a marker of existing disease is impossible to establish. Although the three cohort studies included in the review did show that differences in systolic blood pressure were associated with increased cardiovascular mortality, the effect size (hazard ratio 1·7, 95% CI 1·1–2·5) is of a magnitude that does not exclude the possibility of residual confounding.1 This report has several implications. First, the high specificity (96%) of the association between a difference in systolic blood pressure between arms of more than www.thelancet.com Vol 379 March 10, 2012
Comment
15 mm Hg and peripheral vascular disease justifies use of this measure as a sign of disease. Second, the low sensitivity (15%) shows that measurement of differences is of little value as a screening test for peripheral vascular disease, and ankle-brachial pressure indices will still be necessary for diagnosis. Third, the high prevalence of differences in some of the studies (eg, 7% of participants had an inter-arm difference of 15 mm Hg or higher in one community-dwelling cohort)9 suggests that many people with hypertension will be missed when blood pressure is measured in only one arm. Further research is needed to clarify whether substantial differences between arms should prompt aggressive management of cardiovascular risk factors. Overall, Clark and colleagues’ systematic review and meta-analysis1 supports existing guidelines stating that blood pressure should be measured in both arms. Ascertainment of differences should become part of routine care, as opposed to a guideline recommendation that is mostly ignored.
We declare that we have no conflicts of interest. 1
2
3
4
5
6 7
8
9
Clark CE, Taylor RS, Shore AC, Ukoumunne OC, Campbell JL. Association of a difference in systolic blood pressure between arms with vascular disease and mortality: a systematic review and meta-analysis. Lancet 2012; published online Jan 30. DOI:10.1016/S0140-6736(11)61710-8. Krause T, Lovibond K, Caulfield M, McCormack T, Williams B. Management of hypertension: summary of NICE guidance. BMJ 2011; published online Aug 25. DOI:10.1136/bmj.d4891. Chobanian AV, Bakris GL, Black HR, et al. The seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure: the JNC 7 report. JAMA 2003; 289: 2560–72. Heneghan C, Perera R, Mant D, Glasziou P. Hypertension guideline recommendations in general practice: awareness, agreement, adoption, and adherence. Br J Gen Pract 2007; 57: 948–52. Mancia G, De Backer G, Dominiczak A, et al. 2007 ESH-ESC guidelines for the management of arterial hypertension: the task force for the management of arterial hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC). Blood Press 2007; 16: 135–232. Verberk WJ, Kessels AG, Thien T. Blood pressure measurement method and inter-arm differences: a meta-analysis. Am J Hypertens 2011; 24: 1201–08. Martin U, Holder R, McManus RJ. Right and left arm blood pressure variability: a manifestation of “white coat” effect? British Hypertension Society Annual Scientific meeting; Cambridge, UK; Sept 14–16, 2009: S15. A’Court C, Stevens R, Sanders S, Ward A, McManus R, Heneghan C. Type and accuracy of sphygmomanometers in primary care: a cross-sectional observational study. Br J Gen Pract 2011; 61: e598–e603. Aboyans V, Criqui MH, McDermott MM, et al. The vital prognosis of subclavian stenosis. J Am Coll Cardiol 2007; 49: 1540–45.
*Richard J McManus, Jonathan Mant Department of Primary Care Health Sciences, University of Oxford, Oxford OX1 2ET, UK (RJM); and Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK (JM) [email protected]
Family matters: sexual dimorphism in cardiovascular disease Early identification and management of disease risk is essential to sustain health and quality of life. Several algorithms have been developed to calculate an individual’s risk of coronary heart disease, including the Framingham and the Reynolds risk scores, but these have restricted use in identification of risk for both men and women. Sex-specific determination of risk is crucial in view of the validated sexual dimorphism in incidence, age of onset, progression, treatment efficacy, and morbidity and mortality for coronary artery disease.1–8 The two risk scores share several features. Both algorithms stratify by age, sex, systolic blood pressure, HDL cholesterol, and present smoking status. However, they differ in several important aspects. Whereas the Framingham risk score includes use of drugs for hypertension, the Reynolds risk score includes a measure of inflammation (high-sensitivity C-reactive protein [hs-CRP]) and family history of heart attack before age 60 years—ie, for the Reynolds risk score, your family matters. So what are the inherited genotypes that www.thelancet.com Vol 379 March 10, 2012
affect cardiovascular risk for the individual? Although the Reynolds risk score might slightly improve risk prediction for women compared with the Framingham risk score, can the algorithms be improved to better predict risk for both men and women? In The Lancet, Fadi Charchar and colleagues9 provide insight into genetic variants and potential new approaches to understanding of inheritable coronary artery disease in men. The Y sex chromosome is transmitted from father to son. Genes on the haploid portion (the male-specific region) of the Y chromosome are needed for development of the testes and affect development of hypertension as well as total and LDL cholesterol.10,11 Using material available from more than 3000 unrelated men participating in two large studies in the UK (the cross-sectional British Heart Foundation Family Heart Study, and the prospective West of Scotland Coronary Prevention Study), these investigators identified two haplogroups that accounted for 90% of the variation
Published Online February 9, 2012 DOI:10.1016/S01406736(12)60200-1 See Articles page 915 For more on the Framingham risk score see http://mdcalc. com/framingham-coronaryheart-disease-risk-score-si-units/ For more on the Reynolds risk score see http://www. reynoldsriskscore.org
873