1.1 Background of Study
Hypertension remains a major global public health challenge that has been identified as the leading risk factor for cardiovascular morbidity and mortality (Kearney, Whelton, Reynolds, Muntner, Whelton & He, 2004). It increases hardening of the arteries, thus predisposing individuals to heart diseases, peripheral vascular diseases, stroke, heart failure and kidney failure. Hypertension is the commonest non-communicable disease in the world and all races are affected with variable prevalence. Castelli (2004) explained that its prevalence is on the increase in developing countries where adoption of western lifestyle and stress of urbanization, both of which are expected to increase morbidity associated with unhealthy lifestyle are not on the decline. Andreoli, Carpenter, Grigs and Loscalzo (2004) were of the opinion that hypertension produces disruptions in health, disability and death in the adult population worldwide. Ejike, Ezeanyika and Ugwu (2010) stated that hypertension causes one in every eight deaths worldwide, making it the third leading killer disease in the world. They also estimated that about one billion adults, the world over, had hypertension in the year 2010 and the number is expected to rise to 1.56 billion in the year 2025 if positive intervention programme is not made. Aram, George, Henry, Williams, Lee, and Joseph (2003) indicated that fifty million Americans have high blood pressure, approximately one in three adults.
In United States of America, approximately twenty eight (28) to thirty one per cent of adults have hypertension (Fields, Burt & Cutler (2004). Of this population, 90 to 95 per cent have primary hypertension (high blood pressure related to unidentified cause). The remaining five to tenper cent of this group have secondary hypertension (high blood pressure related to identified cause). In China, almost 130 million people aged 35-74 years are estimated to be hypertensive (Camel &Delene, 2006). Similarly, in Ghana, studies revealed a hypertension prevalence of forty per cent among rural dwellers and eight per cent to thirteen per cent in the urban areas. In sub-Saharan Africa, it is the most rapidly rising cardiovascular disease and affecting over 20 million people (Kadiri, 2005). He also stated that in Nigeria, hypertension is the commonest non-communicable disease with over 4.3 million Nigerians above the age of fifteen years classified as being hypertensive.
Hypertension, also known as high blood pressure is the persistent blood pressure in the arteries above ninety millimetres of mercury (mmHg) between the heart beats (diastolic) or over 140 millimetres of mercury (mmHg) at the beats (systolic) (Aquilla, 2008). According to Hyman and Parlik (2003), hypertension is the persistent raised levels of blood pressure in which the systolic pressure is above 140 mmHg and diastolic pressure above 90 mmHg. The normal blood pressure is below 120/80 mmHg; blood pressure between 120/80 and 139/89 is called ‘Pre-hypertension, and a pressure of 140/90 or above is considered high (abnormal) blood pressure. According to Expert Committee on Non-Communicable Diseases (1993), blood pressure of 120/80 mmHg is considered normal for a 30 year old person, while blood pressure of 140 mmHg is considered high for such a person. Similarly, blood pressure of 150/90 mmHg is considered normal for a 60-year old person, while blood pressure of 160/100 mmHg is high for such a person. Hypertension is sometimes called “the silent killer” because people who have it are often symptom-free. In this study, hypertension is perceived as a systolic blood pressure greater than 140 mmHg and a diastolic blood pressure greater than 90 mmHg among adults. The top number which is the systolic pressure corresponds to the pressure in the arteries as the heart contracts and pumps blood forward into the arteries. The bottom number which is the diastolic pressure represents the pressure in the arteries as the heart relaxes after contraction. The diastolic pressure reflects the lowest pressure to which the arteries are exposed. Blood pressure is normally measured at the brachial artery with a sphygmomanometer (pressure cuff) in millimeters of mercury (mmhg) and given as systolic over diastolic pressure. Hypertension is classified into two namely; primary and secondary hypertension.
According to Stanler (2004), hypertension is categorized into primary and secondary hypertension. Primary hypertension has an unknown cause and accounts for ninety per cent to ninety five per cent of all hypertension cases (Chris, 2009). This type of hypertension is strongly associated with lifestyle. Usually, the patients do not have many signs and symptoms but may experience frequent headache, tiredness, dizziness or nose bleeds. Although the cause is not known, obesity, smoking, alcohol, diet and heredity play a role in essential or primary hypertension. Secondary hypertension has a known cause and accounts for five per cent to ten per cent of all hypertension cases. Chris (2009) maintained that the most common cause of secondary hypertension is an abnormality in the arteries supplying blood to the kidneys. Other causes include airway obstruction during sleep, stress, diseases and tumors of the adrenal glands, lifestyle, spinal cord injury, hormone abnormalities (oral contraceptive estrogen replacement), thyroid disease, toxemia of pregnancy, renal problems such as vascular lesion of renal arteries, diabetic neuropathy, pains as well as anxiety and hypoglycemia. There are some factors which predispose adults to hypertension.
The risk factors of hypertension are genetic factor which can be inherited from parents, age which when the body does not retain the amount of elasticity as it used to in the early years of life, obesity which is an increase in weight of over ten per cent above normal body index due to generalized deposition of fat in the body, excessive salt intake which increases blood pressure, stress which produces chemical substances that cause generalized vasoconstriction, oral contraceptive which contains estrogen that causes salt retention that increases the volume of blood, sedentary lifestyle which has the tendency of increasing body weight and directly raises blood pressure, elevated levels of plasma lipids particularly cholesterol, excessive alcohol consumption which increases blood pressure and tobacco use (cigarette smoking) that contains nicotine which causes constriction of the blood vessels. The signs and symptoms of hypertension recognized by Thatch and Schultz (2004) include occipital headache, dizziness, restlessness, failing vision, shortness of breath, and rapid increased heartbeat. Adults should possess the knowledge of risk factors in order to prevent hypertension. This will help them recognize and prevent or treat hypertension when these signs occur.