Moderately Elevated Blood Pressure: A Systematic Review [Internet]

Review
Stockholm: Swedish Council on Health Technology Assessment (SBU); 2008 Sep. SBU Yellow Report No. 170/1U.

Excerpt

Prevalence of High Blood PressureAn estimated 1.8 million people in Sweden, or 27% of the adult population (aged 20 or older), have high blood pressure (hypertension). The condition is just as common among women as men.Of the 1.8 million Swedish adults with elevated blood pressure:60% have mild hypertension (140–159/90–99 mm Hg)30% have moderate hypertension (160–179/100–109 mm Hg)10% have severe hypertension (≥180/≥110 mm Hg)Studies in Sweden find that the number of patients who reach the treatment goal of blood pressure below 140/90 mm Hg rarely exceeds 20–30% of those who have been prescribed blood pressure lowering drugs.Risk Factor for Cardiovascular DiseaseElevated blood pressure is a risk factor for coronary heart disease, stroke and other cardiovascular disease, including heart failure (Evidence Grade 1). High blood pressure is also a risk factor for dementia (Evidence Grade 3).An increase of 20 mm Hg in systolic pressure or 10 mm Hg in diastolic pressure above 115/75 mm Hg doubles the risk of death from cardiovascular disease (Evidence Grade 1). The increase is independent of other risk factors for cardiovascular disease, and it is similar for women and men (Evidence Grade 1).Women have a lower absolute risk of cardiovascular disease than men (Evidence Grade 1). However, blood pressure lowering treatment reduces relative risk equally in women and men (Evidence Grade 1).Guidelines in Different CountriesThe guidelines released in various countries over the past few years for the management of hypertension are largely in agreement. The guidelines are basically the same for women and men. All guidelines:Stress the importance of reaching the treatment goal of blood pressure below 140/90 mm Hg – below 130/80 mm Hg for patients with diabetes and/or renal disease.Emphasise the need to consider the patients total risk of cardiovascular disease rather than treating high blood pressure in isolation.Recommend a low-dose thiazide diuretic as the first-line therapy or as one of several first-line therapies.Lifestyle Changes as the Basis of Successful TreatmentWith or without concurrently lowering blood pressure, a number of lifestyle changes – including physical activity, weight loss, dietary modifications, stress management, smoking cessation and the avoidance of excessive alcohol consumption – can minimise the risk factors for cardiovascular disease (Evidence Grade 1).Lifestyle measures can reduce the need for drug therapy and should form the basis for treating people with high blood pressure (hypertensives) (Evidence Grade 1). Smoking cessation measures should also be a priority for hypertensives and can generate major treatment benefits (Evidence Grade 1).Pharmacological TreatmentBlood pressure lowering treatment reduces the risk of stroke, myocardial infarction and premature death in hypertensives of both sexes (Evidence Grade 1).The various groups of blood pressure lowering drugs – thiazide diuretics, angiotensin converting enzyme (ACE) inhibitors, calcium antagonists, angiotensin receptor blockers (ARBs) and beta blockers – ordinarily used in Sweden are equally effective (reduction of approximately 10/5 mm Hg) when administered separately (Evidence Grade 1).Since the efficacy of different types of drugs can vary for a particular individual, switching to or adding one or more medications may be required in order to lower blood pressure sufficiently.For people with uncomplicated hypertension, all the major drug groups – thiazide diuretics, ACE inhibitors, calcium antagon- ists and ARBs – are equally effective in minimising the risk of cardiovascular disease (Evidence Grade 1). Beta blockers reduce the risk of stroke to a lesser extent (Evidence Grade 1). That is partly due to poorer reduction in blood pressure (Evidence Grade 2).Following stroke, blood pressure lowering drugs reduce the risk of myocardial infarction (Evidence Grade 3) and stroke recurrence (Evidence Grade 1). Treatment is equally effective with or without concurrent hypertension.At least half of all patients with type 2 diabetes also have hypertension. The effect of hypertension treatment on the absolute risk of cardiovascular disease morbidity and mortality is greater with concurrent diabetes (Evidence Grade 1).In people with type 2 diabetes, the impact on relative risk is also greater (Evidence Grade 1).Patients whose treatment is based on drugs (ACE inhibitors and ARBs) that directly affect the renin-angiotensin-aldosterone system are less likely to develop type 2 diabetes than those whose treatment is based on a thiazide diuretic combined with a beta blocker or on a calcium antagonist (Evidence Grade 2).In patients with high risk (multiple risk factors) of cardiovascular disease and concurrent type 2 diabetes mellitus, blockade of the renin–angiotensin–aldosterone system may reduce the risk beyond the impact of simply lowering blood pressure (ACE inhibitors – Evidence Grade 2, ARBs – Evidence Grade 3).Blood pressure lowering treatment counteracts clinically relevant deterioration of renal function (Evidence Grade 1). No difference with regard to the long-term effect on renal function has been shown among the various groups of blood pressure lowering drugs in patients who have mild to moderate hypertension without other concurrent kidney complications. This report did not review treatment of patients with diabetes and impaired renal function.Hypertension leads to thickening of the heart muscle. Blood pressure lowering treatment reduces left ventricular mass (Evidence Grade 1). Such a reduction is associated with a lower risk of cardiovascular disease (Evidence Grade 2).Economic AspectsSales of blood pressure lowering drugs for the indication of hypertension more than doubled from 70 defined daily doses (DDSs) per 1 000 Swedes in 1992 to 155 in 2002. Costs for drug treatment of hypertension totalled SEK 1,656 million in 2002.Since satisfactory treatment of everyone with hypertension would involve both a larger number of patients and more medications per person, total drug costs would rise (Evidence Grade 2).Choice of medication has a major impact on both drug costs and cost effectiveness. Prescribing the least expensive equiva- lent medication whenever possible would reduce drug costs and improve cost effectiveness compared with current pre- scription patterns (Evidence Grade 2).Treatment of uncomplicated hypertension with the least expensive equivalent drug entails cost savings for older women, as well as middle-aged and older men. Improving the treatment of patients with moderate to high risk is more cost-effective than treating more people with low risk (Evidence Grade 2).Ethical aspectsThe ethical dilemma of treating an apparently healthy person with drugs for what is likely to be a long period of time should be weighed against the risks associated with withholding treatment that may prevent serious disease. Principles of Evidence Grading Quality refers to the scientific quality of a particular study and its ability to reliably answer a specific question. Evidence Grade refers to the total scientific evidence for a conclusion, i.e., how many high-quality studies support the conclusion. Evidence Grade 1 A conclusion assigned Evidence Grade 1 is supported by at least two studies with high quality among the total scientific evidence. If some studies are at variance with the conclusion, the evidence grade may be lower. Evidence Grade 2 A conclusion assigned Evidence Grade 2 is supported by at least one study with high quality and two studies with moderate quality among the total scientific evidence. If some studies are at variance with the conclusion, the evidence grade may be lower. Evidence Grade 3 A conclusion assigned Evidence Grade 3 is supported by at least two studies with moderate quality among the total scientific evidence. If some studies are at variance with the conclusion, the evidence grade may be lower.

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