w High Blood Pressure Guidelines Create New At-Risk Classification

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1 Journal of Cardiovascular Nursing Vol. 19, No. 6, pp LippincoltWilliams SWilkins, Inc. w High Blood Pressure Guidelines Create New At-Risk Classification Changes in Blood Pressure Classification by JNC 7 Edgar R. Miller III, MD, PhD Megan L. Jehn, MHS High blood pressure has become increasingly prevalent and is an important risk factor for cardiovascular disease. The Seventh Report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) has redefined normal blood pressure as less than 120/80 mm Hg and created a new blood pressure category called "prehypertension" for those with a systolic BP of 120 to 139 mm Hg or a diastolic BP of 80 to 89 mm Hg. This new blood pressure category was created to identify adults considered to be at risk for developing hypertension and to alert both patients and healthcare providers of the importance of adopting lifestyle changes. Recognition of prehypertension provides important opportunities to prevent hypertension and cardiovascular disease. KEYWORDS: hypertension, JNC 7, lifestyle modification, prehypertension The American Heart Association recently released its "Top 10" list of iifesaving advances for At the top of this list was the Seventh Report of the Joint National Committee on the Prt'vcnrion., Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7}.''" This publication is the seventh in the past 30 years initiated by the JNC to provide consensus guidelines to increase awareness, prevention, treatment., and control of blood pressure (BP). The JNC 7 report provides a comprehensive discussion of the evidence-based guidelines for the prevention and management of hypertension. An important new change in JNC 7 is the EdgarR. Miller III, MD, PhD Associate Professor of Medicme, -Welch Center for Prevention, Epidemiology and Clinical Research, The Johns Hopkins Medical Institutions. Baltimore, Md. Megan L. Jehn, MHS Doctoral Candidate, Department of Epidemiology, The Johns ^ Hopkins Bloomberg School of Public Health, Baltimore, Md. I" The authors have no conflict of interest. Corresponding author Edgar R. Miller III, MD, PhD, Welch Center for Prevention, Epidemiology and Clinical Research, The Johns Hopkins Medical Institutions, 2024 E Monument St, Suite 2-624, Baltimore, MD _ ( ermiller@welch.jhu.edu). reclassification of BP and creation of a new category of adults with "prehypertension." This new BP category was created to identify adults considered to be at risk for developing hypertension and to alert both patients and healthcare providers to the importance of adopting lifestyle interventions. Reclassification of Blood Pressure A goal of the JNC 7 report was to simplify the classification of BP and provide guidelines that would be more useful to clinicians. Suboptimal BP control rates in the United States for the past decade have, in part, been blamed on the complexity of the existing guidelines leading to confusion over treatment goals. Efforts to simplify and create mtjre descriptive BP categories have evolved over the last 3 reports (Table!). Previously, BP was considered "normal" if systolic and diastolic BPs were less than 140 mm Hg and 90 mm Hg, respectively, and "optimal" if they were less than 120 mm Hg and 80 mm Hg, respectively. Under the new guidelines, "normal" BP is now what was previously described as "optimal" BP, and a new category designated as "prehypertension" has been added. 367

2 368 Journal of Cardiovascular Nursing I November/December 2004 JABLE 1 it Changes in JNC Classification of Blood Press- Systolic Blood Pressure JNC-5(1993)* JNC-6 (1997)^ JNC-7 (2003)* <120 mm Hg mm Hg mm Hg mm Hg mm Hg > mm Hg >210 mm Hg Normal High-normal Stage 1 (mild) Stage 2 (moderate) Stage 3 (severe) Stage 4 (very severe) Optimal Normal High-normal Stage 1 (mtid) Stage 2 (moderate) Stage 3 (severe) Normal Prehypertension Stage 1 Stage 2 *From the fifth report, ^From the sixth report.' *From Chobanian et a\ The prehypertension category includes those with previously "normal" or "high-normal" BP- a systolic BP between 120 and 139 mm Hg or a diastolic BP between 80 and 89 mm Hg. A reclassification of benign-sounding designations to a more ominous category of "prehypertension" is intended to alert patients and healthcare providers of the high probability that patients in this category will develop hypertension. Epidemiological Evidence Supporting the Redassification of Blood Pressure The reclassification of BP in the new guidelines was prompted by several influential observational studies and clinical trials published during the last several years, specifically, new data demonstrating increased cardiovascular risk for blood pressure levels previously considered normal, as well as new data on the lifetime risk of hypertension. Recent data frtjm the Framingham Heart Study suggests that 55-year-old adults have a 90% probability of developing hypertension in their lifetime and a 60% probability of receiving antihypertensive medications/ This study included men and women who were nonhypertensive at age years and who survived to years. Of equal concern as the substantial lifetime risk of hypertension is the evidence of consistent and graded associations between even moderately elevated BP and increased cardiovascular risk. Another report from the Framingham Heart Study, cited in the JNC 7 report, found that individuals with BP in the range of /85-89 mm Hg (considered highnormal according to JNC-6 classification) have a 2- fold increased risk of cardiovascular disease compared with individuals with BP values below 120/80.'^ Consistent with this report is a recent metaanaiysis of 61 epidemiological studies that included over 1 million individuals from 40 to 89 years of age. Results from this study indicate that the risk of death from cardiovascular disease and stroke increases linearly with increasing BP beginning as low as 115/75 mm Hg and, second, that for each increment of 20/10 mm Hg the risk of cardiovascular disease doubles/ These studies clearly suggest that the adverse health effects of increased BP begin at much lower levels than initially believed. Opportunities for Prevention The reclassification of BP will result in approximately 60 million Americans who previously believed that they had normal BP to be now classified as "prehypertensive."^ Given the large number of adults included in this group, targeting prehypertensives with strategies proven to prevent the development of hypertension and BP-related complications has enormous public health implications. Unlike patients diagnosed with hypertension, there is no evidence that antihypertensive medications are beneficial in patients with prehypertension. However, there is substantial evidence that lifestyle modifications can be very successful in reducing BP'' Therefore, the JNC 7 report states that all patients who are prehypertensive should be "firmly and unambiguously advised to practice lifestyle modification." Lifestyle Modification for the Prevention of Hypertension The specific nonpharmacological therapies advocated by JNC 7 are based on the results of efficacy studies demonstrating benefit in preventing hypertension. With the exception of physical activity (regular aerobic physical activity, for a minimum of 30 minutes, on most days of the week), most lifestyle recommendations are nutrition-based and include (1) reduction of dietary sodium consumption to less than 100 mmol/d (2.4 g/d); (2) weight loss (for overweight and obese persons) and weight control (for nonoverweight); (3) moderation of alcohol intake (<2 drinks per day for men and <1 drink per day ftjr women); and (4) adoption of the Dietary Approaches to Stop Hypertension (DASH) diet (Table 1).^

3 Changes in Blood Pressure Classification by JNC The documented reduction in systolic BP for each of the lifestyle recommendations based on the results of meta-analyses is illustrated in Figure 1. These reductions represent the net difference between the baseline and follow-up systolic BPs for the intervention and control groups in the hypertensive subgroup. The smallest reductions in BP were observed for calcium and magnesium supplementation, while the largest BP reductions were observed for trials of multiple, simultaneous interventions and the DASH diet. Reduced alcohol consumption was associated with a mean reduction in systolic BP of 3.9 mm Hg (95% Cl, ) in a metaanalysis of 15 clinical trials.'^ Weight reduction was associated with systolic and diastolic BP reductions of 4.7 mm Hg (95% CI, ) in a meta-analysis of 17 clinical trials." A meta-analysis of 54 clinical trials of physical activity showed similar reductions in systolic BP': 4.9 mm Hg (95% CI, ).'^ The DASH trial was a multicenter randomized feeding study to test the effects of different dietary feeding patterns on BP.'' Participants were randomized to one of the following diets: (1) a control diet low in fruits, vegetables, and dairy products; (2) a diet rich in fruits and vegetables; or (3) a "combination" (aka DASH} diet high in fruits, vegetables, and low-fat dairy products. In those with hypertension, the combination diet reduced systolic BP 11.4 mm Hg ( mm Hg) more than the control diet.'-' Sodium intake has also been consistently associated with BP. Reductions in dietary sodium (76 mmol reduction in sodium excretion per 24 hours) resulted m a 4.8 mm Hg decrease (95% CI, mm Hg) in systolic BP in a meta-analysis of 22 clinical trials.' ^ These findings were corroborated by the DASH- Sodium Trial results. In this controlled feeding study, participants were randomized to a diet high in fruits, vegetables, and low-fat dairy or the typical American diet, and each group also received 3 different levels of sodium in random order. In this trial, reductions in sodium intake from the high to intermediate group resulted in reductions of systolic BP of 2.1 mm Hg for those on the control diet and 1.3 mm Hg or those on the DASH diet."*^ Other dietary recommendations that have been shown to have small effects on BP, but are not currently recommended by the National High Blood Pressure Education Program,'' include fish oil supplementation,"^ magnesium supplementation,'"^ calcium supplementation,''' and potassium supplementation.'** In addition to studies testing the efficacy of modifying a single risk factor, a trial of comprehensive lifestyle modification, including simultaneous weight loss, increased physical activity, reduced sodium intake, and reduced alcohol consumption has recently been published.'^ In the PREMIER clinical trial, nonhypertensive participants who were randomized to a behavioral intervention incorporating information on all established lifestyle interventions in addition to information on the DASH diet, had a reduction in systolic BP of 6.3 mm Hg (95% CI, mm Hg) compared with those who were randomized to the advice-only group over a 6-month period. This trial suggested that not only is this approach beneficial, it is also highly feasible. A healthcare visit provides an unusually powerful setting to advocate lifestyle modification, and lifestyle FIGURE 1. Net change in systolic hlood pressure for different interventions from meta-analyses of calcium supplementatioti, magnesium supplementation, alcohol reduction, potassium supplementation, weight loss, physical activity, and sodium reduction and from subgroup analyses of the PREMIER clinical trial and the Dietary Approaches to Stop Hypertension (DASH) trial. Trials were conducted in different study populations and are not directly?^^^'*

4 370 Journal of Cardiovascular Nursing November/December 2004 modifications should have considerable appeal over being diagnosed and treated for hypertension. Officebased treatment of high BP using nonpharmacological strategies can be accomplished, but success is dependent upon several factors. The skills of the physicians, nurses, and staff., available resources, organizational structure of the office, and patients' willingness to change are of primary importance. Summary The new JNC 7 classification of "prehyperrensive" assigns patients a high risk for developing hypertension. Such intentional branding of patients may help remind healthcare providers to advocate and motivate patients to adopr nonpharmacological measures to prevent the inevitability of developing hypertension. The most effective approach to prevent the development of hypertension includes a combination of lifestyle changes (Table 2). While the impact of the new prehypertensive category at facilitating lifestyle changes is untested, it may help to provide a counseling tool to help motivate patients to adopt lifestyle changes in an attempt to avoid or delay medication. The development of the prehypertension category by the JNC 7 is the culmination of many important scientific studies documenting the adverse effects of BP at levels thar were previously assumed to be normal. Previously categorizing these patients as normotensive may have lulled patients and providers into a false sense of security and decreased utilization of effective primary prevention strategies. Recognition of the TABLE 2 Lifestyle Recommendations for the Primary Prevention of Hypertension and the Management of Hypertension*'^'^'^" Intervention Recommendation Dietary sodium Reduce dietary sodium intake to iess than reduction 100 mmol/d (2.4 g/d) Weight loss Maintain healthy body weight: BMI 18-24,9 Moderation of Limit alcohol consumption to <2 drinks per d alcohol (loz or 30 ml ethanol) in most men consumption and no more than 1 drink per day in women and lightweight persons Physical activity Engage in regular aerobic physicai activity for at least 30 mm per day, most days of the week Adopt DA5H Consume a diet rich in fruits and dietary plan vegetables and iow-fat dairy products with a reduced content of saturated and total fat Dietary potassium Maintain adequate intake of potassium maintenance (>90 mmol [3500 mg]) per day *BMI indicates body mass index; DASH, Dietary Approaches to Stop Hypertension. importance of moderately elevated BP levels provides important opportunities to prevent hypertension and blood-pressure-reiated complications. 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5 Changes in Blood Pressure Classification by JNC Jee SH, Miller HR 111, Guallar E. et al. The cttect of I"). Whdron PK, He J, Cutler JA, et ill. Et-'feas of oral porasmagnesilim supplementation on blood pressure: a meta- sium on blood pressure. Mera-analysis of randomized conanalysis of randomized clinical trials. Am j Hypertens. trolled clinical trials. ^AMA. 1997;277(20): ;15(8): ' 20. Sacks FM, Svetkey LP, Vollmer WM, et al. Effects on 1 8. Appel LJ, Champagne CM,, Harsha DW, et al. Kffects of blood pressure of reduced dietary sodium and the Dietary comprehensive lifestyle modification on blood pressure Approncbes to Stop Hypertension (DASH) diet. DASHcontrol: main results of the PREMIER clinical trial. Sodium C;ollaborative Research Group. N Eiig,l / Med. }AMA. 2003;289(16):2083~ ;344( l):3-10.

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