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.[1] 

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.[1]

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.[1]

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 [11]), 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.[1]

Initial assessment
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:
•    Urinalysis. 
•    Blood chemistry (potassium, sodium, and creatinine). 
•    Standard 12-lead electrocardiography to assess for left ventricular hy­pertrophy or concomitant evidence of previous myocardial infarction.[1] 

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.[1] 

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.[1] 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.[3] 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.[2] 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.[3] 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%).[8]

Lifestyle modifications
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.[11] Table 1  [12]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.”[15]

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”[18] and CHEP.[15] The DASH diet is known to result in substantial reductions in blood pressure, even when sodium intake is not reduced.[19] 

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),[20] 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.[21] 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.[22] Limited literacy is likely with four or more incorrect answers[22] 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 [13] 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). 

Summary
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.

Competing interests
None declared.