ABSTRACT: Hypertension can be diagnosed from blood pressure measurement in the office or home, or from ambulatory 24-hour blood pressure measurement, provided that recommended equipment and measurement techniques are used in all cases. A history, physical examination, and routine laboratory tests are needed to exclude less common secondary causes of hypertension and to determine whether target organ damage has occurred. Following diagnosis, lifestyle modifications involving healthy eating, sodium reduction, and increased physical activity can be helpful in managing and preventing hypertension. A comprehensive, structured, multidisciplinary approach that simultaneously addresses all key factors within the context of a holistic health perspective has been found to sustain effective change. Many affordable tools, techniques, and resources that encourage patient self-management are available provincewide to support such an approach.
Patients should be encouraged to take advantage of the many resources that support patients who need to limit sodium intake, engage in more physical activity, and make other changes to prevent and control high blood pressure.
Manual office blood pressure (BP) measurement can be used to diagnose hypertension when readings from three separate visits are averaged and the systolic blood pressure (SBP) is equal to or greater than 160 mm Hg, or the diastolic blood pressure (DBP) is equal to or greater than 100 mm Hg. Hypertension can also be diagnosed when readings from five visits are averaged and the SBP is equal to or greater than 140 mm Hg, or the DBP is equal to or greater than 90 mm Hg.
While elevated BP from more than one reading is required for a diagnosis of hypertension, a single reading can be enough to identify hypertensive urgency or a hypertensive emergency, conditions that require immediate management. The features of a hypertensive crisis include asymptomatic DBP elevation equal to or greater than 130 mm Hg or hypertensive encephalopathy (associated headache, irritability, alteration in consciousness, and other manifestations of CNS dysfunction) or the presence of marked blood pressure elevation in association with conditions such as acute aortic dissection, acute left ventricular failure, or acute myocardial ischemia.
Hypertension may also be diagnosed with additional blood pressure measurement in out-of-office settings. Ambulatory BP measurement (ABPM) should be considered when an office-induced increase in BP is suspected or BP readings in the office fluctuate. Hypertension can be diagnosed using an ABPM, when the average awake SBP is equal to or greater than 135 mm Hg, or the average DBP is equal to or greater than 85 mm Hg. Hypertension is also diagnosed when the average 24-hour SBP is equal to or greater than 130 mm Hg, or the average DBP is equal to or greater than 80 mm Hg.
Home BP measurement can be used to diagnose hypertension as well, as long as the clinician ensures that the patient is using an approved device (http://hypertension.ca/chep/approved-home-bp-device), the patient follows proper procedures, and, preferably, the device can print out the reading. If all these conditions are met, home measurement of BP can be used to diagnose hypertension when the average SBP is equal to or greater than 135 mm Hg, or the average DBP is equal to or greater than 85 mm Hg.
When assessing patients for hypertension, a history should be taken and a physical examination performed to identify any associated conditions (diabetes mellitus, dyslipidemia, chronic kidney disease) and target organ damage from hypertension (stroke, chronic kidney disease, retinopathy, cardiac disease). Importantly, the history and physical examination can help establish whether the patient has secondary causes of hypertension, such as coarctation of the aorta or Cushing syndrome. Exogenous factors that can induce or aggravate hypertension should be identified and managed if possible (see “Assessing and managing resistant hypertension” in this issue).
Routine laboratory tests should be performed for the investigation of all patients with hypertension:
• Blood chemistry (potassium, sodium, and creatinine).
• Standard 12-lead electrocardiography to assess for left ventricular hypertrophy or concomitant evidence of previous myocardial infarction.
Tests for risk stratification should also be performed—a fasting blood glucose test and a fasting lipids test (total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides)—to determine the patient’s global cardiovascular risk.
Investigations for secondary causes of hypertension should be initiated for patients with clinical features or laboratory findings suggestive of severe hypertension or hypertension resistant to multiple medications. Additional investigation is indicated for patients with increased probability of secondary hypertension.
Labile hypertension accompanied by headache, palpitations, and diaphoresis suggests the possibility of pheochromocytoma. The detection of abdominal bruit, especially lateralized to the renal area, suggests renovascular disease. Truncal obesity with purple striae suggests Cushing syndrome. Abnormalities on routine clinical tests, such as hypokalemia, suggest the possibility of primary aldosteronism; hypercalcemia suggests possible hyperparathyroidism; and elevated creatinine or abnormal urinalysis can indicate renal disease. While the majority of patients do not have a specific cause for hypertension, it is important to consider the possibility of a secondary cause.
Hypertension in older patients
Hypertension in older patients merits special consideration because of the high prevalence of hypertension in older age groups, and the increasing proportion of older persons in Canada.
Concepts are changing about the pathophysiology of hypertension in older age groups, with growing acceptance of the dominant role of aging-induced changes in arterial structure and the function of large vessels.[2,3] The fracture of the individual elastin lamellae with aging is known to play a role in the stiffening and dilatation of large arteries. The consequence of stiffer arteries is that reflection waves return earlier to the heart and lead to an augmentation of aortic systolic pressure. This explains the increased prevalence of isolated systolic hypertension in older individuals.
The augmentation of SBP increases myocardial oxygen demand and increases the loading condition on the heart, which in turn accentuates myocardial ischemia and the development of cardiac hypertrophy. Arterial stiffness–induced increased SBP with a decrease in DBP results in an increase in pulse pressure that can produce more damage in organs such as the brain and kidney, where the vasculature cannot dampen the increased pulse pressure to the same extent possible in some other organs. The ensuing microvascular damage contributes to chronic kidney disease and vascular cognitive impairment.[4,5]
Evidence that antihypertensive drug therapy in older individuals with hypertension can reduce cardiovascular morbidity and mortality suggests that the changes in arterial structure with aging are not immutable but can be modified, and that blood pressure reduction is of value across the age spectrum. In randomized controlled trials in patients over 60 years of age, a diuretic or dihydropyridine calcium channel blocker or an ACE inhibitor, but not beta-blockers, significantly reduced cardiovascular events and mortality.[6,7]
In patients who were 80 years of age or older and had a sustained systolic blood pressure of 160 mm Hg or more, active treatment with a diuretic followed by an ACE inhibitor when necessary was associated with a significant fall in all-cause mortality (21%), death from cardiovascular causes (23%), rate of fatal or nonfatal stroke (30%), and a reduction in the rate of heart failure (64%).
Authors of major position statements and systematic literature reviews have concluded that healthy eating, active living, and achieving a healthy weight have a major impact on prevention and management of hypertension.[1,9-14] More specifically, the risk factors of overweight, physical inactivity, and high sodium intake appear to be major independent contributors to hypertension.[10,11,14] Indeed, clustering these risk factors into low-risk or high-risk groupings allows us to identify individuals at high or low risk of developing hypertension. Table 1 shows the evidence-based recommendations for lifestyle modifications that have the greatest impact on preventing and managing hypertension.
The Canadian Hypertension Education Program (CHEP) recommends that “Hypertensive patients and normotensive individuals at increased risk of developing hypertension consume a diet that emphasizes fruits, vegetables and low-fat dairy products, dietary and soluble fibre, whole grains and protein from plant sources and that is reduced in saturated fat and cholesterol.”
The DASH (Dietary Approaches to Stop Hypertension) diet,[16,17] which was developed specifically to address hypertension and traditionally referenced as the recommended dietary guideline along with other DASH-like diets, is very similar (although not identical) to the current recommendations found in “Eating Well with Canada’s Food Guide” and CHEP. The DASH diet is known to result in substantial reductions in blood pressure, even when sodium intake is not reduced.
Best practices and patient resources
Supporting patients who are making lifestyle changes aimed at preventing or managing hypertension calls for a comprehensive, structured, multidisciplinary, and sustained approach. The expanded Chronic Care Model (CCM), which integrates population health promotion with the prevention and management of chronic disease, helps individuals cope with a disease and develop skills for health and wellness.
CCM also provides strategies in the community and in the health system to support self-management. An individual’s ability to read, understand, and use health care information to make informed decisions about disease prevention, self-care, and treatment is one of the most important factors influencing health status. Establishing a patient’s level of health literacy is critical for determining how best to customize your approach. A quick and accurate primary care screening tool, the Newest Vital Sign, consists of six questions about a nutrition label. Limited literacy is likely with four or more incorrect answers and this undoubtedly translates into poor patient compliance with recommendations for changes in diet.
Clinicians can support self-management and help patients access appropriate, culturally sensitive, clear, and affordable resources and supports in the community. Table 2 contains practical suggestions physicians can provide to patients, and resources they can recommend to manage the key lifestyle modifications that will help prevent and control hypertension: healthy eating, sodium reduction, physical activity, healthy weight, moderate alcohol consumption, and stress management. Two province-wide services are highly recommended as evidence-based practice supports for physicians who do not have ready access to registered dietitians and CSEP-certified exercise physiologists for their patients—Dietitian Services at HealthLink BC and the Physical Activity Line (PAL).
Once appropriate BP measurement has confirmed a diagnosis of hypertension, clinical assessment and routine laboratory testing can stratify the patient’s risk by identifying any associated conditions or hypertension-induced target organ damage. Following risk stratification, lifestyle changes should be recommended for all patients with hypertension. A large number of resources are available to help clinicians support patient lifestyle changes and self-management that can aid in controlling blood pressure.
1. Daskalopoulou SS, Khan NA, Quinn RR, et al. The 2012 Canadian Hypertension Education Program (CHEP) recommendations for the management of hypertension: Blood pressure measurement, diagnosis, assessment of risk and therapy. Can J Cardiol 2012;28:1-38.
2. Aronow WS, Fleg JL, Pepine CJ, et al. ACCF/AHA 2011 expert consensus document on hypertension in the elderly: A report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents developed in collaboration with the American Academy of Neurology, American Geriatrics Society, American Society for Preventive Cardiology, American Society of Hypertension, American Society of Nephrology, Association of Black Cardiologists, and European Society of Hypertension. J Am Soc Hypertens 2011;5:259-352.
3. O’Rourke MF, Hashimoto J. Mechanical factors in arterial aging: A clinical perspective. J Am Coll Cardiol 2007;50:1-13.
4. O’Rourke MF, Safar ME. Relationship between aortic stiffening and microvascular disease in brain and kidney: Cause and logic of therapy. Hypertension 2005;46:200-204.
5. Rabkin SW, Jarvie G. Comparison of vascular stiffness in vascular dementia, Alzheimer dementia and cognitive impairment. Blood Press 2011;20:274-283.
6. Medical Research Council trial of treatment of hypertension in older adults: Principal results. MRC Working Party. BMJ 1992;304:405-412.
7. Staessen JA, Fagard R, Thijs L, et al. Randomised double-blind comparison of placebo and active treatment for older patients with isolated systolic hypertension. The Systolic Hypertension in Europe (Syst-Eur) Trial Investigators. Lancet 1997;350(9080):757-764.
8. Beckett NS, Peters R, Fletcher AE, et al. Treatment of hypertension in patients 80 years of age or older. New Engl J Med 2008;358:1887-1898.
9. Cardiometabolic Risk Working Group: Executive Committee, Leiter LA, Fitchett DH, Gilbert RA, et al. Cardiometabolic Risk in Canada: A detailed analysis and position paper by the Cardiometabolic Risk Working Group. Can J Cardiol 2011;27:e1-e33.
10. 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;289:2560-2572. Erratum in: JAMA 2003;290:197.
11. Forman JP, Stampfer MJ, Curhan GC. Diet and lifestyle risk factors associated with incident hypertension in women. JAMA 2009;302:401-411.
12. Savica V, Bellinghieri G, Kopple JD. The effect of nutrition on blood pressure. Ann Rev Nutr 2010;30:365-401.
13. Touyz RM, Campbell N, Logan A, et al.; Canadian Hypertension Education Program. The 2004 Canadian recommendations for the management of hypertension: Part III—Lifestyle modifications to prevent and control hypertension. Can J Cardiol 2004;20:55-59.
14. Dickinson HO, Mason JM, Nicolson DJ, et al. Lifestyle interventions to reduce raised blood pressure: A systematic review of randomized controlled trials. J Hypertens 2006;24:215-233.
15. The Canadian Hypertension Education Program. Lifestyle management. Accessed 10 July 2012. http://hypertension.ca/chep/therapies/lifestyle-management/.
16. Sacks FM, Svetkey LP, Vollmer WM, et al., for the DASH-Sodium Collaborative Research Group. Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. N Engl J Med 2001;344:3-10.
17. U.S. Department of Health and Human Services. In brief: Your guide to lowering your blood pressure with DASH. Accessed 10 July 2012. www.nhlbi.nih.gov/health/public/heart/hbp/dash/dash_brief.pdf.
18. Eating Well with Canada’s Food Guide. Accessed 10 July 2012. www.hc-sc.gc.ca/fn-an/food-guide-aliment/index-eng.php.
19. Vollmer WM, Sacks FM, Ard J, et al. Effects of diet and sodium intake on blood pressure: Subgroup analysis of the DASH-Sodium trial. Ann Intern Med 2001;135:1019-1028.
20. Barr VJ, Robinson S, Marin-Link B, et al. The expanded Chronic Care Model: An integration of concepts and strategies from population health promotion and Chronic Care Model. Hosp Q 2003;7:73-82.
21. Health literacy in Canada: A healthy understanding. Ottawa: Canadian Council on Learning; 2008. Accessed 10 July 2012. www.ccl-cca.ca/pdfs/HealthLiteracy/HealthLiteracyReportFeb2008E.pdf.
22. Weiss BD, Mary Z, Mays MZ, et al. Quick assessment of literacy in primary care: The newest vital sign. Ann Fam Med 2005;3:514-522.
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