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INTRODUCTION

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Hypertension accounts for 6% of deaths worldwide. In Canada, the overall prevalence of hypertension was 22% and was higher in men (26%) than in women (18%) in a survey done between 1986 and 1992.1 Hypertension prevalence increases progressively with age, being lower in women than men aged 18 to 34 years (2% vs.11%) and aged 35 to 64 years (21% vs. 31%).1,2 However, in the group aged 65 to 74, women had a higher prevalence than men (58% vs. 56%). The overall prevalence of hypertension in the United States in 2004 was 72 000 000 (33 000 000 males; 39 000 000 females). A higher percentage of men than women have hypertension until age 45 years. The percentage of hypertension is similar in men and women between the ages of 45 and 54. After the age of 54, a higher percentage of women have hypertension than men. It is estimated that middle-aged North Americans have a 90% life-time risk of developing hypertension. The prevalence of hypertension is higher in southeastern United States as compared to other regions.3 Hypertension in black men and women in the southern states is higher (35–34%) as compared to other parts of the United States (27–33%). The prevalence of hypertension in white men and women in the southern United States is slightly higher (21.5% to 26.5%) as compared to other parts of the United States (21% to 24.3%). When Canadian survey data were compared to similar data from the United States, hypertension prevalence was similar between the two countries (20.1% vs. 21.1%, Canadian vs. American), but awareness of the diagnosis (69% vs. 57%), and treatment of hypertension (52% vs. 34%) were substantially higher in the United States than in Canada.1 Recent data from the United States show a further improvement in treatment and control rates. There was a large increase in diagnosis (51%) and treatment (66%) of hypertension between 1994 and 2003.4 There is substantial evidence that the patient management guidelines are not followed frequently, and the current practice patterns present a major barrier to treatment and control of hypertension.5 It is not only the treatment practice but also the pathophysiology of the disease that affects the outcome. There has been advancement in understanding the mechanism of the disease and in diagnostic and treatment modalities. This chapter will deal with the definition of hypertension, measurement of blood pressure, epidemiology, pathophysiology, complications, and treatment.

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DEFINITION AND CLASSIFICATION OF HYPERTENSION

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The higher the pressure, the worse the prognosis. The prognosis is based not on whether hypertension is thought to be present, but on the actual recorded pressure. However the question is "At what pressure level should treatment be instituted?" The dividing line between normotension and hypertension is arbitrary. The decision to treat should be based on the evaluation of risk. The reason for a dividing line is to initiate treatment. The risk associated with blood ...

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