Report from the Canadian Chronic Disease Surveillance System: Hypertension in Canada, 2010

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Introduction

Hypertension

Hypertension is a chronic condition that occurs when blood pressure is consistently high for long periods of time, leading to the damage of arteries and decreased blood flow to affected organs. Blood pressure is the pressure or force of blood against the walls of blood vessels as it circulates. It is expressed as two numbers: systolic blood pressure (the top or higher number) is the pressure in the artery when the heart contracts and diastolic blood pressure (the bottom or lower number) is the pressure in the artery when the heart relaxes between beats. Hypertension is defined as systolic blood pressure greater or equal to 140 mmHg or diastolic blood pressure greater or equal to 90 mmHg.⁴ For individuals with diabetes or chronic kidney disease, hypertension is defined as blood pressure over 130 mmHg systolic or over 80 mmHg diastolic.

Known as the “silent killer”, hypertension is a leading modifiable risk factor for cardiovascular disease and mortality in the world. In most cases, hypertension has no symptoms and can only be diagnosed through proper blood pressure measurement. If left untreated, hypertension can increase a person’s risk of stroke, coronary heart disease, dementia, heart and kidney failure and other chronic diseases.^{5 6}

Hypertension affects all age groups, but the risk of hypertension increases with age. For example, over their remaining lifetime, 90% of middle-aged and older men and women participating in the Framingham Heart Study, a longitudinal cohort study, were likely to develop hypertension.⁷ However, finding high blood pressure early, treating and keeping it in the normal range can reduce the risk of developing complications. Even a small decrease in blood pressure can reduce the risk of developing complications such as heart failure, stroke and other cardiovascular diseases.^{5 8}

The risk of developing hypertension can be reduced through a healthy diet, limiting sodium intake, avoiding excessive alcohol consumption, losing excess weight, managing stress and exercising regularly.

For individuals with hypertension, it can be controlled with lifestyle modifications and/or use of blood pressure lowering medication. Moreover, it is important for these individuals to have cholesterol, blood sugar and kidney function checked on a regular basis as the presence of these risk factors increases the risk of damage from hypertension.

Hypertension and diabetes frequently co-exist, along with other cardiovascular disease risk factors such as obesity and high levels of lipids or fats in the blood. People who have multiple risk factors are more likely to have a heart attack or stroke compared with those who do not. ⁹

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⁴ Public Health Agency of Canada. Tracking heart disease and stroke in Canada [Internet]. Ottawa: Public Health Agency of Canada; 2009 [cited 2009 Dec 7]. 118p. Available from: www.phac-aspc.gc.ca/publicat/2009/cvd-avc/pdf/cvd-avs-2009-eng.pdf (pdf)
⁵ MacMahon S, Peto R, Cutler J, Collins R, Sorlie P, Neaton J, et al. Blood pressure, stroke, and coronary heart disease. Part 1. Prolonged differences in blood pressure: prospective observational studies corrected for the regression dilution bias. Lancet. 1990; 335 (8692): 765-74.
⁶ Duron E, Hanon O. Hypertension, cognitive decline and dementia. Arch Cardiovasc Dis. 2008;101(3):181-9.
⁷ Vasan RS, Beiser A, Seshadri S, Larson MG, Kannel WB, D’Agostino RB, et al. Residual lifetime risk for developing hypertension in middle-aged women and men: The Framingham Heart Study. JAMA. 2002; 287 (8):1003-10.
⁸ Blood Pressure Canada [homepage on the Internet]. [cited 2009 Dec 7]. Available from: www.hypertension.ca/bpc/blood-pressure-information/about
⁹ Australian Institute of Health and Welfare. Chronic diseases and associated risk factors in Australia [Internet]. Canberra: Australian Institute of Health and Welfare; 2006 November. [cited 2009 Dec 7]. 82 p. Available from: www.aihw.gov.au/publications/index.cfm/title/10319

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