DISCUSS THE EPIDEMIOLOGY OF HYPERSION IN NIGERIA
The number of people living with hypertension (high blood pressure) is predicted to be 1.56 billion worldwide by the year 2025. In Nigeria alone, about a third of all people over the age of 20 years have hypertension, as measured by high blood pressure and taking antihypertensive medications in 2011-2012.
Control of hypertension has become a key national priority in the US as part of the Million Hearts initiative from the Department of Health and Human Services, which aims to prevent 1 million heart attacks and strokes in the US by 2017.3
An increasing prevalence of the condition is blamed on lifestyle factors, such as physical inactivity, a salt-rich diet created by processed and fatty foods, and alcohol and tobacco use.
hypertension, is a chronic medical condition in which the blood pressure in the arteries is persistently elevated. Blood pressure is expressed by two measurements, the systolic and diastolic pressures, which are the maximum and minimum pressures, respectively, in the arterial system. The systolic pressure occurs when the left ventricle is most contracted; the diastolic pressure occurs when the left ventricle is most relaxed prior to the next contraction. Normal blood pressure at rest is within the range of 100–140 millimeters mercury (mmHg) systolic and 60–90 mmHg diastolic. Hypertension is present if the blood pressure is persistently at or above 140/90 mmHg for most adults; different numbers apply to children.
Hypertension usually does not cause symptoms initially, but sustained hypertension over time is a major risk factor for hypertensive heart disease, coronary artery disease, stroke, aortic aneurysm, peripheral artery disease, and chronic kidney disease.
EPIDEMIOLOGY OF HYPERSION IN NIGERIA
Hypertension is having a blood pressure higher than 140 over 90 mmHg, a definition shared by all the medical guidelines. This means the systolic reading (the pressure as the heart pumps blood around the body) is over 140 mmHg (millimeters of mercury) or the diastolic reading (as the heart relaxes and refills with blood) is over 90 mmHg. While this threshold has been set to define hypertension, it is for clinical convenience and because achieving targets below this level brings benefits for patients.
The blood flowing inside vessels exerts a force against the walls – this is blood pressure.
Hypertension is classified as either primary (essential) hypertension or secondary hypertension. About 90–95% of cases are categorized as primary hypertension, defined as high blood pressure with no obvious underlying cause. The remaining 5–10% of cases are categorized as secondary hypertension, defined as hypertension due to an identifiable cause, such as chronic kidney disease, narrowing of the aorta or kidney arteries, or an endocrine disorder such as excess aldosterone, cortisol, or catecholamines.
Dietary and lifestyle changes can improve blood pressure control and decrease the risk of health complications, although treatment with medication is still often necessary in people for whom lifestyle changes are not enough or not effective. The treatment of moderately high arterial blood pressure (defined as >160/100 mmHg) with medications is associated with an improved life expectancy. The benefits of treatment of blood pressure that is between 140/90 mmHg and 160/100 mmHg are less clear, with some reviews finding no benefit and others finding benefit.
Signs and symptoms
Hypertension is defined as a systolic blood pressure (SBP) of 140 mm Hg or more, or a diastolic blood pressure (DBP) of 90 mm Hg or more, or taking antihypertensive medication.
Based on recommendations of the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7), the classification of BP for adults aged 18 years or older has been as follows :
• Normal: Systolic lower than 120 mm Hg, diastolic lower than 80 mm Hg
• Prehypertension: Systolic 120-139 mm Hg, diastolic 80-89 mm Hg
• Stage 1: Systolic 140-159 mm Hg, diastolic 90-99 mm Hg
• Stage 2: Systolic 160 mm Hg or greater, diastolic 100 mm Hg or greater
Hypertension may be primary, which may develop as a result of environmental or genetic causes, or secondary, which has multiple etiologies, including renal, vascular, and endocrine causes. Primary or essential hypertension accounts for 90-95% of adult cases, and secondary hypertension accounts for 2-10% of cases.
The evaluation of hypertension involves accurately measuring the patient’s blood pressure, performing a focused medical history and physical examination, and obtaining results of routine laboratory studies. A 12-lead electrocardiogram should also be obtained. These steps can help determine the following :
• Presence of end-organ disease
• Possible causes of hypertension
• Cardiovascular risk factors
• Baseline values for judging biochemical effects of therapy
Other studies may be obtained on the basis of clinical findings or in individuals with suspected secondary hypertension and/or evidence of target-organ disease, such as CBC, chest radiograph, uric acid, and urine microalbumin.
Many guidelines exist for the management of hypertension. Most groups, including the JNC, the American Diabetes Associate (ADA), and the American Heart Association/American Stroke Association (AHA/ASA) recommend lifestyle modification as the first step in managing hypertension.
JNC 7 recommendations to lower BP and decrease cardiovascular disease risk include the following, with greater results achieved when 2 or more lifestyle modifications are combined :
• Weight loss (range of approximate systolic BP reduction [SBP], 5-20 mm Hg per 10 kg)
• Limit alcohol intake to no more than 1 oz (30 mL) of ethanol per day for men or 0.5 oz (15 mL) of ethanol per day for women and people of lighter weight (range of approximate SBP reduction, 2-4 mm Hg)
• Reduce sodium intake to no more than 100 mmol/day (2.4 g sodium or 6 g sodium chloride; range of approximate SBP reduction, 2-8 mm Hg)
• Maintain adequate intake of dietary potassium (approximately 90 mmol/day)
• Maintain adequate intake of dietary calcium and magnesium for general health
• Stop smoking and reduce intake of dietary saturated fat and cholesterol for overall cardiovascular health
• Engage in aerobic exercise at least 30 minutes daily for most days (range of approximate SBP reduction, 4-9 mm Hg)
The AHA/ASA recommends a diet that is low in sodium, is high in potassium, and promotes the consumption of fruits, vegetables, and low-fat dairy products for reducing BP and lowering the risk of stroke. Other recommendations include increasing physical activity (30 minutes or more of moderate intensity activity on a daily basis) and losing weight (for overweight and obese persons).
The 2013 European Society of Hypertension (ESH) and the European Society of Cardiology (ESC) guidelines recommend a low-sodium diet (limited to 5 to 6 g per day) as well as reducing body-mass index (BMI) to 25 kg/m2 and waist circumference (to < 102 cm in men and < 88 cm in women).
If lifestyle modifications are insufficient to achieve the goal BP, there are several drug options for treating and managing hypertension. Thiazide diuretics are the preferred agents in the absence of compelling indications.
Compelling indications may include high-risk conditions such as heart failure, ischemic heart disease, chronic kidney disease, and recurrent stroke, or those conditions commonly associated with hypertension, including diabetes and high coronary disease risk. Drug intolerability or contraindications may also be factors. An angiotensin-converting enzyme (ACE) inhibitor, angiotensin receptor blocker (ARB), calcium channel blocker (CCB), and beta-blocker are all acceptable alternative agents in such compelling cases.
The following are drug class recommendations for compelling indications based on various clinical trials :
• Heart failure: Diuretic, beta-blocker, ACE inhibitor, ARB, aldosterone antagonist
• Postmyocardial infarction: Beta-blocker, ACE inhibitor, aldosterone antagonist
• High coronary disease risk: Diuretic, beta-blocker, ACE inhibitor, CCB
• Diabetes: Diuretic, beta-blocker, ACE inhibitor, ARB, CCB
• Chronic kidney disease: ACE inhibitor, ARB
• Recurrent stroke prevention: Diuretic, ACE inhibitor
Hypertension is a leading cause of morbidity and mortality in Africa, and Nigeria, the most populous country in the continent, hugely contributes to this burden. The problems caused by hypertension are made worse, according to WHO, when people are not aware of the necessity for – or unable to afford – regular blood pressure checks. “We hope this campaign will encourage more adults to check their blood pressure but also that health authorities will make blood pressure measurement affordable for everyone,” said Dr Shanthi Mendis, a medical officer at WHO.
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