Curr Hypertens Rep (2014) 16:418 DOI 10.1007/s11906-014-0418-z
THERAPEUTIC TRIALS (B PITT, SECTION EDITOR)
Should Patients with Obesity and Hypertension be Treated Differently from Those Who Are Not Obese? Michael J. Bloch & Anthony J. Viera
Published online: 6 February 2014 # Springer Science+Business Media New York 2014
Abstract Obesity and hypertension frequently coexist. Measuring blood pressure (BP) accurately in obese patients is challenging and may require strategies that are less accurate, such as forearm cuffing or use of wrist cuffs. Pathophysiologic mechanisms of hypertension may differ between obese and non-obese individuals, which may result in differing effects of common BPlowering medications. However, to date, there is insufficient trial data to recommend a different approach to medication selection based on body mass index. Additionally, the goal BP is generally not different between obese and non-obese patients. Weight loss should be emphasized for obese patients with hypertension, and interventions in addition to diet and exercise may include weight loss medications and bariatric surgery. Recognition and treatment of obstructive sleep apnea is also important.
Keywords Hypertension . Obesity . Body mass Index . Blood pressure measurement . Ambulatory blood pressure monitoring . Home blood pressure monitoring . Obstructive sleep apnea . Sympathetic nervous system . Renin angiotensin system . Adiposity . Arm circumference . Blood pressure cuff This article is part of the Topical Collection on Therapeutic Trials M. J. Bloch Department of Medicine, University of Nevada School of Medicine, Reno, NV, USA M. J. Bloch (*) Renown Institute for Heart & Vascular Health, Renown Regional Medical Center, 1155 Mill Street, Reno, NV 89502, USA e-mail: [email protected] A. J. Viera Department of Family Medicine, University of North Carolina School of Medicine, Chapel Hill, USA A. J. Viera Hypertension Research Program, University of North Carolina, Chapel Hill, USA
size . Obesity paradox . Weight loss . Blood pressure goals . ACCOMPLISH blood pressure study . Polysomnogram Abbreviations BMI body mass index BP blood pressure CVD cardiovascular disease
Introduction Approximately two-thirds of adults in the United States have a body mass index (BMI) greater than 25 kg/m2, which categorizes them as overweight or obese (BMI >30 kg/m2) [1]. In 2011–2012, 35 % of U.S. adults were obese [2]. A recent meta-analysis (2.88 million individuals) demonstrated that, relative to normal weight, BMI of greater than 35 kg/m2 conveys nearly 30 % greater risk of all-cause mortality [3]. The cost of obesity and its health-related problems are a substantial societal burden. Obese adults have nearly 40 % more visits to primary care physicians and nearly 50 % more inpatient hospital days per year [4, 5]. Annual medical expenditures for obese adults are 36 % higher than for normalweight adults, and it is estimated that the government shoulders half of the total costs [6]. Hypertension is one of the most significant risk factors for cardiovascular disease (CVD) across all categories of body size and weight, but among the many health problems associated with obesity, hypertension is one of the most common. Obese individuals tend to have volume expansion mediated by sodium retention and neurohumoral mechanisms, which lead to hypertension through increased cardiac output [7]. Obesity-related increases in sympathetic nervous system activity may be mediated by increased insulin resistance, adipokines (e.g., leptin), and obstructive sleep apnea, among
418, Page 2 of 7
others. With the rising prevalence of obesity comes rising prevalence of hypertension, with some estimates attributing 60 % to 70 % of hypertension to adiposity [8]. Increased central adiposity is particularly associated with increases in blood pressure (BP). For every 4.5 cm increase in waist circumference for men or 2.5 cm for women, systolic BP increases 1 mm Hg [9]. Obese patients tend to have other cardiovascular comorbidities (e.g., diabetes, hyperlipidemia) as well which, together, place them at increased overall cardiovascular risk. Given the common co-occurrence of obesity and hypertension, the variety of mechanisms that elevate BP that may be unique to obese individuals, and the potentially increased CVD risk among this subpopulation, it is worth considering whether patients with obesity and hypertension should be treated differently from those who are not obese. Relevant questions include, (1) should the goal BP be different for obese patients with hypertension; (2) are certain antihypertensive medications preferred for obesity-related hypertension; and (3) what other management approaches should be considered for obesity-related hypertension?
Measurement of Blood Pressure in Obese Patients Without accurate measurement of BP, the question of in whom to start treatment and how aggressively to treat high BP becomes moot. By convention, office BP is generally measured in the upper extremity with a patient seated. Accurate measurement of BP is difficult in obese patients, particularly those who are severely obese or who have unusual arm anatomy. Along with the increasing prevalence of obesity, there is a corresponding increase in arm circumference, necessitating the use of alternative cuff sizes for many patients. Data from the National Health and Nutrition Examination Surveys (NHANES) demonstrate that the mean arm circumference increased from 31.8 to 32.8 cm in the years from 1988 to 2000 [10]. According to NHANES, by 2007–2010, the mean arm circumference had increased to 34.2 cm for men and 31.9 cm for women. [11]. Consensus recommendations for BP measurement have been published and widely distributed. [12]. Table 1 illustrates the recommended cuff sizes based upon arm circumference. Ideally, the cuff used for ausculatory BP measurement should have a bladder length that is 80 % and width that is 40 % of the arm circumference. Based on this preferred ratio of 2:1 length to width, the optimal bladder width for a large adult cuff would be 20 cm. However, given the relative short length of the upper arm in most Americans, a cuff width of 20 cm is not considered clinically practical, and as such, all recommended cuffs have a width of 16 cm. Based on 2007–2010 data from NHANES, 42.9 % of men and 25.3 % of women require a large adult cuff, and 1.9 % of
Curr Hypertens Rep (2014) 16:418 Table 1 Recommended cuff size based on arm circumference from AHA Council on High Blood Pressure Research Scientific Statement (Pickering) Arm circumference (cm)
Cuff size
Cuff dimensions (cm)
22–26 27–34 35–44 45–52
Small adult Adult Large adult Adult thigh
12x22 16x30 16x36 16x42
men and 2.8 % of women require a thigh cuff [11]. While the exact prevalence of use of an undersized bladder, also known as ‘undercuffing,’ is unknown, it is likely common in routine clinical practice. The clinical implications of using the wrong cuff size can be substantial. A recent review of the literature has suggested that undercuffing can result in a range of error from 3.2/2.4–12/8 mm Hg, with reports of overestimations as high as 30 mm Hg in individual patients [13]. These data suggest that obese patients may be overtreated, with the attendant risks of increased pharmacologic therapy, merely based upon the choice of office BP cuff. There is increased interest across the spectrum of hypertensive patients in utilizing home and ambulatory BP monitoring. Out-of-office measurements are particularly challenging in obese individuals. Until recently, most commercially available home BP devices came with only a normal-sized adult cuff; large cuffs are usually sold separately and add additional cost and complexity to home BP measurement. Most home and ambulatory BP monitors use an oscillometric technique rather than the auscultatory technique used in the office, and the effect of arm circumference on accuracy of oscillometric monitors is less well known. By altering their algorithm, future oscillometric devices may be able to provide accurate BP measurements in obese patients with a singlesized cuff, but in general, the same recommendations hold true for choosing an appropriate cuff size for out-of-office (both home and ambulatory) BP measurement as for office auscultatory measurement. [14]. Centers that employ ambulatory BP monitoring need to have a wide range of cuff sizes available as well as staff trained to use the appropriate cuff size based on arm circumference. The importance of choosing an appropriate cuff size for outof-office BP measurement was highlighted by a recent report that examined the incidence of masked hypertension diagnosis in subjects with large arms [15]. In this analysis, hypertension status differed significantly based on the use of either standard or large-sized adult cuffs for home BP monitoring. Using an inappropriately sized normal adult cuff led to a 56.6 % incidence of sustained hypertension and a 15.1 % incidence of masked hypertension, but use of an appropriately sized large
Curr Hypertens Rep (2014) 16:418
adult cuff decreased the incidence of sustained hypertension to 41.5 % and masked hypertension to 7.5 %. In patients with morbid obesity, arm circumference of >52 cm is not uncommon. In this circumstance, one can consider placing a cuff around the forearm and auscultating over the radial artery, but the accuracy of this method is highly variable. The shape of the upper arm in obese patients may be problematic as well. For most patients, the cylindrical-shaped cuffs commonly found in physicians’ offices are appropriate. However, when the arm circumference near the shoulder is much greater than at the elbow (more conical shape) a cylindrical cuff may overestimate BP [13]. Conical cuffs have been evaluated in small series of obese patients, but these products are generally not yet available for clinical use [13, 14, 16]. Although rarely performed due to patient inconvenience and invasiveness, intra-arterial measurement of BP is an option for patients for whom there is no other way to accurately assess their BP. Measurement of BP at the wrist with automated oscillometric devices is increasingly popular for home BP monitoring. The reported accuracy of wrist monitors has been varied, and there is great debate within the BP monitoring community with regard to their general utility relative to arm devices. With that having been said, for many obese patients, wrist monitors may be the only way to obtain a reasonably accurate BP reading. If wrist monitors are to be employed, either in the office or at home, care must be taken to ensure that the appropriate technique is used, particularly with regard to positioning of the arm. Of note, these devices are generally designed for patients with wrists of 22 cm or smaller. Some patients with morbid obesity may have wrist sizes too large for accurate readings with these monitors.
Blood Pressure Goals According to JNC 7, the European Society of Hypertension and European Society of Cardiology, and the National Institute for Health and Clinical Excellence (NICE), the goal BP for most patients with hypertension is
THERAPEUTIC TRIALS (B PITT, SECTION EDITOR)
Should Patients with Obesity and Hypertension be Treated Differently from Those Who Are Not Obese? Michael J. Bloch & Anthony J. Viera
Published online: 6 February 2014 # Springer Science+Business Media New York 2014
Abstract Obesity and hypertension frequently coexist. Measuring blood pressure (BP) accurately in obese patients is challenging and may require strategies that are less accurate, such as forearm cuffing or use of wrist cuffs. Pathophysiologic mechanisms of hypertension may differ between obese and non-obese individuals, which may result in differing effects of common BPlowering medications. However, to date, there is insufficient trial data to recommend a different approach to medication selection based on body mass index. Additionally, the goal BP is generally not different between obese and non-obese patients. Weight loss should be emphasized for obese patients with hypertension, and interventions in addition to diet and exercise may include weight loss medications and bariatric surgery. Recognition and treatment of obstructive sleep apnea is also important.
Keywords Hypertension . Obesity . Body mass Index . Blood pressure measurement . Ambulatory blood pressure monitoring . Home blood pressure monitoring . Obstructive sleep apnea . Sympathetic nervous system . Renin angiotensin system . Adiposity . Arm circumference . Blood pressure cuff This article is part of the Topical Collection on Therapeutic Trials M. J. Bloch Department of Medicine, University of Nevada School of Medicine, Reno, NV, USA M. J. Bloch (*) Renown Institute for Heart & Vascular Health, Renown Regional Medical Center, 1155 Mill Street, Reno, NV 89502, USA e-mail: [email protected] A. J. Viera Department of Family Medicine, University of North Carolina School of Medicine, Chapel Hill, USA A. J. Viera Hypertension Research Program, University of North Carolina, Chapel Hill, USA
size . Obesity paradox . Weight loss . Blood pressure goals . ACCOMPLISH blood pressure study . Polysomnogram Abbreviations BMI body mass index BP blood pressure CVD cardiovascular disease
Introduction Approximately two-thirds of adults in the United States have a body mass index (BMI) greater than 25 kg/m2, which categorizes them as overweight or obese (BMI >30 kg/m2) [1]. In 2011–2012, 35 % of U.S. adults were obese [2]. A recent meta-analysis (2.88 million individuals) demonstrated that, relative to normal weight, BMI of greater than 35 kg/m2 conveys nearly 30 % greater risk of all-cause mortality [3]. The cost of obesity and its health-related problems are a substantial societal burden. Obese adults have nearly 40 % more visits to primary care physicians and nearly 50 % more inpatient hospital days per year [4, 5]. Annual medical expenditures for obese adults are 36 % higher than for normalweight adults, and it is estimated that the government shoulders half of the total costs [6]. Hypertension is one of the most significant risk factors for cardiovascular disease (CVD) across all categories of body size and weight, but among the many health problems associated with obesity, hypertension is one of the most common. Obese individuals tend to have volume expansion mediated by sodium retention and neurohumoral mechanisms, which lead to hypertension through increased cardiac output [7]. Obesity-related increases in sympathetic nervous system activity may be mediated by increased insulin resistance, adipokines (e.g., leptin), and obstructive sleep apnea, among
418, Page 2 of 7
others. With the rising prevalence of obesity comes rising prevalence of hypertension, with some estimates attributing 60 % to 70 % of hypertension to adiposity [8]. Increased central adiposity is particularly associated with increases in blood pressure (BP). For every 4.5 cm increase in waist circumference for men or 2.5 cm for women, systolic BP increases 1 mm Hg [9]. Obese patients tend to have other cardiovascular comorbidities (e.g., diabetes, hyperlipidemia) as well which, together, place them at increased overall cardiovascular risk. Given the common co-occurrence of obesity and hypertension, the variety of mechanisms that elevate BP that may be unique to obese individuals, and the potentially increased CVD risk among this subpopulation, it is worth considering whether patients with obesity and hypertension should be treated differently from those who are not obese. Relevant questions include, (1) should the goal BP be different for obese patients with hypertension; (2) are certain antihypertensive medications preferred for obesity-related hypertension; and (3) what other management approaches should be considered for obesity-related hypertension?
Measurement of Blood Pressure in Obese Patients Without accurate measurement of BP, the question of in whom to start treatment and how aggressively to treat high BP becomes moot. By convention, office BP is generally measured in the upper extremity with a patient seated. Accurate measurement of BP is difficult in obese patients, particularly those who are severely obese or who have unusual arm anatomy. Along with the increasing prevalence of obesity, there is a corresponding increase in arm circumference, necessitating the use of alternative cuff sizes for many patients. Data from the National Health and Nutrition Examination Surveys (NHANES) demonstrate that the mean arm circumference increased from 31.8 to 32.8 cm in the years from 1988 to 2000 [10]. According to NHANES, by 2007–2010, the mean arm circumference had increased to 34.2 cm for men and 31.9 cm for women. [11]. Consensus recommendations for BP measurement have been published and widely distributed. [12]. Table 1 illustrates the recommended cuff sizes based upon arm circumference. Ideally, the cuff used for ausculatory BP measurement should have a bladder length that is 80 % and width that is 40 % of the arm circumference. Based on this preferred ratio of 2:1 length to width, the optimal bladder width for a large adult cuff would be 20 cm. However, given the relative short length of the upper arm in most Americans, a cuff width of 20 cm is not considered clinically practical, and as such, all recommended cuffs have a width of 16 cm. Based on 2007–2010 data from NHANES, 42.9 % of men and 25.3 % of women require a large adult cuff, and 1.9 % of
Curr Hypertens Rep (2014) 16:418 Table 1 Recommended cuff size based on arm circumference from AHA Council on High Blood Pressure Research Scientific Statement (Pickering) Arm circumference (cm)
Cuff size
Cuff dimensions (cm)
22–26 27–34 35–44 45–52
Small adult Adult Large adult Adult thigh
12x22 16x30 16x36 16x42
men and 2.8 % of women require a thigh cuff [11]. While the exact prevalence of use of an undersized bladder, also known as ‘undercuffing,’ is unknown, it is likely common in routine clinical practice. The clinical implications of using the wrong cuff size can be substantial. A recent review of the literature has suggested that undercuffing can result in a range of error from 3.2/2.4–12/8 mm Hg, with reports of overestimations as high as 30 mm Hg in individual patients [13]. These data suggest that obese patients may be overtreated, with the attendant risks of increased pharmacologic therapy, merely based upon the choice of office BP cuff. There is increased interest across the spectrum of hypertensive patients in utilizing home and ambulatory BP monitoring. Out-of-office measurements are particularly challenging in obese individuals. Until recently, most commercially available home BP devices came with only a normal-sized adult cuff; large cuffs are usually sold separately and add additional cost and complexity to home BP measurement. Most home and ambulatory BP monitors use an oscillometric technique rather than the auscultatory technique used in the office, and the effect of arm circumference on accuracy of oscillometric monitors is less well known. By altering their algorithm, future oscillometric devices may be able to provide accurate BP measurements in obese patients with a singlesized cuff, but in general, the same recommendations hold true for choosing an appropriate cuff size for out-of-office (both home and ambulatory) BP measurement as for office auscultatory measurement. [14]. Centers that employ ambulatory BP monitoring need to have a wide range of cuff sizes available as well as staff trained to use the appropriate cuff size based on arm circumference. The importance of choosing an appropriate cuff size for outof-office BP measurement was highlighted by a recent report that examined the incidence of masked hypertension diagnosis in subjects with large arms [15]. In this analysis, hypertension status differed significantly based on the use of either standard or large-sized adult cuffs for home BP monitoring. Using an inappropriately sized normal adult cuff led to a 56.6 % incidence of sustained hypertension and a 15.1 % incidence of masked hypertension, but use of an appropriately sized large
Curr Hypertens Rep (2014) 16:418
adult cuff decreased the incidence of sustained hypertension to 41.5 % and masked hypertension to 7.5 %. In patients with morbid obesity, arm circumference of >52 cm is not uncommon. In this circumstance, one can consider placing a cuff around the forearm and auscultating over the radial artery, but the accuracy of this method is highly variable. The shape of the upper arm in obese patients may be problematic as well. For most patients, the cylindrical-shaped cuffs commonly found in physicians’ offices are appropriate. However, when the arm circumference near the shoulder is much greater than at the elbow (more conical shape) a cylindrical cuff may overestimate BP [13]. Conical cuffs have been evaluated in small series of obese patients, but these products are generally not yet available for clinical use [13, 14, 16]. Although rarely performed due to patient inconvenience and invasiveness, intra-arterial measurement of BP is an option for patients for whom there is no other way to accurately assess their BP. Measurement of BP at the wrist with automated oscillometric devices is increasingly popular for home BP monitoring. The reported accuracy of wrist monitors has been varied, and there is great debate within the BP monitoring community with regard to their general utility relative to arm devices. With that having been said, for many obese patients, wrist monitors may be the only way to obtain a reasonably accurate BP reading. If wrist monitors are to be employed, either in the office or at home, care must be taken to ensure that the appropriate technique is used, particularly with regard to positioning of the arm. Of note, these devices are generally designed for patients with wrists of 22 cm or smaller. Some patients with morbid obesity may have wrist sizes too large for accurate readings with these monitors.
Blood Pressure Goals According to JNC 7, the European Society of Hypertension and European Society of Cardiology, and the National Institute for Health and Clinical Excellence (NICE), the goal BP for most patients with hypertension is
