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Walsh J, McDonald KM, Shojania KG, et al. Closing the Quality Gap: A Critical Analysis of Quality Improvement Strategies (Vol. 3: Hypertension Care). Rockville (MD): Agency for Healthcare Research and Quality (US); 2005 Jan. (Technical Reviews, No. 9.3.)

Cover of Closing the Quality Gap: A Critical Analysis of Quality Improvement Strategies (Vol. 3: Hypertension Care)

Closing the Quality Gap: A Critical Analysis of Quality Improvement Strategies (Vol. 3: Hypertension Care).

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The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC 7), issued in 2003, defines hypertension as a systolic blood pressure (SBP) greater than 140 mmHg and diastolic blood pressure (DBP) greater than 90 mmHg ( > 140/90), compared with a normal blood pressure of < 120/80. This revised threshold represents a marked departure from the former standard for hypertension ( < 140/90).1 A new category—“pre-hypertension”—also was established for patients with a SBP of 120 to139 mmHg, or a DBP of 80 to 89 mmHg. Hypertension often exhibits no clinical manifestations until the onset of organ damage, therefore screening, early detection, and proper disease control are critical to good health. The World Health Organization (WHO) credits hypertension with one in every eight deaths, making it the third leading cause of death worldwide,2 and has described high blood pressure as “...the most important public health problem in developed countries.”3 In the United States, 28.7 percent of participants in the 1999-2000 National Health and Nutrition Examination Survey (NHANES) conducted by the National Center for Health Statistics were identified as hypertensive, either because they had elevated blood pressure, or because they were being treated with antihypertensive medications. Extrapolating from these findings, it is estimated that 58.4 million Americans have the condition. Hypertension is the most common primary diagnosis in the United States, and was the principal diagnosis for 35 million office visits during 2001.4

Hypertension is a major risk factor for cardiovascular disease,57 including coronary heart disease (CHD), heart failure, and stroke. The benefits of treating hypertension have been established for many years, and treatment standards have evolved continually. A 1990 meta-analysis of 14 randomized treatment trials of hypertensive patients showed that a 5–6 mmHg reduction in DBP could translate to a 42 percent reduction in stroke occurances.8 A 1990 epidemiologic review reported that a lower blood pressure should confer a lower risk of vascular disease.9 Other major trials reported a significant overall decrease in cardiac events following treatment for hypertension, including the Systolic Hypertension in the Elderly Program (SHEP) (a 27 percent reduction),10 the Swedish Trial in Older Patients with Hypertension (STOP) (a 13 percent reduction),11 and the Medical Research Council study (MRC) (a 19 percent reduction).12

While exact projections are difficult to establish, data from the Framingham Heart Study and the NHANES II indicate that even small improvements in blood pressure control can have a major impact on public health. Lowering the DBP by only 2 mmHg could result in a 6 percent reduction in the risk of coronary heart disease, and a 15 percent reduction in the risk of stroke and transient ischemic attacks.13 Moreover, in individuals with a SBP of 140–159 mmHg and/or a DBP of 90–99 mmHg, a sustained 12 mm reduction in SBP for a period of 10 years has been estimated to prevent one death among every 11 patients treated.1

Important advances in hypertension care have occurred in the last ten to fifteen years. Previously, hypertension was generally treated only when the DBP exceeded 90 mmHg. But the 1991 publication of the SHEP study confirmed the benefits of treating isolated systolic hypertension.10 More recently, pooled individual data from 61 separate prospective studies confirmed the risks associated with an elevated SBP: for individuals aged 40–69, each increase of 20 mmHg of SBP (or 10 mmHg DBP) was associated with a two-fold increase in mortality from both CHD and stroke.14 SBP is a robust indicator of risk of cardiovascular disease in the population at large. It is also a stronger predictor of risk than DBP, in those older than age 50.15 Current guidelines call for treating isolated systolic hypertension according to the same principles used in the general care of hypertension.1 The therapeutic focus now is on achieving the SBP target goal, as most patients then will reach the DBP goal.1 Lifestyle modifications and drug therapy are recommended for all patients with blood pressures above the normal range.

The prevalence of hypertension increases with age and tends to be higher among women.16 And while hypertension affects all races and ethnic groups, certain groups bear a disproportionate burden of risk. non-Hispanic blacks have higher rates of hypertension than do non-Hispanic whites and Mexican-Americans, while Mexican-Americans have the lowest reported rates of controlled hypertension.16 Blacks tend to develop high blood pressure at an earlier age, they generally have much higher blood pressures,17 and they have a four times higher age-adjusted risk of end-stage renal disease than do whites.18

Drug therapy for high blood pressure is equally effective among men and women.19 Blacks who receive appropriate treatment achieve overall decreases in blood pressure similar to those of whites, and also may experience a lower incidence of cardiovascular disease.17, 20, 21 Appropriate treatment and control of hypertension also reduces the risk of several associated complications, including end-stage renal disease, congestive heart failure, and peripheral vascular disease. The target blood pressures are less than 130/80 mmHg for hypertensive patients with diabetes or renal disease, and less than 140/90 mmHg for other patients with hypertension.

This review provides a systematic assessment of the effect of various quality improvement (QI) strategies on the screening and treatment of hypertension.

The Quality Gap

Despite clear evidence that treating hypertension reduces morbidity and mortality, the incidence of stroke, myocardial infarction, and heart failure, hypertension care in the United States often fails to comply with evidence-based guidelines.1 And while 68.9 percent of the participants in the 1999-2000 NHANES study were aware of their hypertension, only 58.4 percent were receiving treatment.16

These rates are an improvement over those reported from 1991-1998, but they still are not optimal. The national wellness program, Healthy People 2010,22 includes four important goals for the detection and evaluation of hypertension:

  • Reduce the proportion of U.S. adults with high blood pressure from the current rate of 28.7 percent,16 to 16 percent.22
  • Increase the proportion of hypertensive adults with controlled blood pressure from the current rate of 31 percent,16 to 50 percent.22
  • Increase the proportion of adults with high blood pressure who are taking action to help control their blood pressure (i.e., losing weight, increasing physical activity, or reducing sodium intake) from the current rate of 82 percent,23 to 95 percent.22
  • Increase to 95 percent the proportion of adults who have had their blood pressure measured in the preceding two years and can state whether their blood pressure is normal or high.22

Recent findings suggest the nation is approaching this last goal. Data from the National Health Interview Survey, collected from 2001-2003, indicate 90 percent of all adults had their blood pressure measured in the previous two years and could state whether or not it is high.23

Evidence-based Guidelines and Quality of Care Measures


Many aspects central to high blood pressure detection, evaluation, and treatment have been studied and the findings have contributed to the development of one of the most extensive guidelines processes available: the JNC Reports.1, 17 These guidelines are developed by the National High Blood Pressure Education Program of the National Heart, Lung, and Blood Institute, along with a number of coordinating committee member organizations.1

Therapy for hypertension is largely pharmaceutical-based, although nonpharmacologic therapies and lifestyle modifications such as exercise, sodium restriction, weight loss, and modification of alcohol intake are important contributors to blood pressure reduction. Evidence-based guidelines for management of hypertension recommend a wide variety of antihypertensive drugs, as well as targets for blood pressure control. The JNC 7 guidelines state “there are excellent clinical outcome trial data proving that lowering blood pressure with several classes of drugs, including angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor antagonists (ARBs), β-adrenergic receptor antagonists (β-blockers), calcium channel antagonists (CCBs), and thiazide-type diuretics, will all reduce the complications of hypertension.”1 Equivalent blood pressure reduction with different antihypertensive agents, however, may not confer the same degree of risk reduction.24 A recent analysis of data from 29 randomized trials studied the comparative benefits of several different antihypertensive drug classes on risk of cardiovascular events.25 This analysis showed a reduction in major cardiovascular events with ACE inhibitors, angiotensin receptor antagonists, β-adrenergic receptor antagonists, calcium channel antagonists, and thiazide-type diuretics, while further determining that larger reductions in blood pressure (regardless of which of these medications was used) resulted in larger reductions in risk.25 The JNC 7 guidelines further contend that “diuretics have been virtually unsurpassed in preventing the cardiovascular complications of hypertension,” and recommends that “thiazide-type diuretics should be used as initial therapy for most patients with hypertension, either alone or in combination with one of the other classes (ACE inhibitors, ARBs, β-blockers, CCBs) demonstrated to be beneficial in randomized controlled outcome trials.”1

A complete discussion of the different antihypertensive therapies is beyond the scope of this review of quality improvement strategies. Readers are directed to the JNC 7 guidelines and to other published resources. The World Health Organization and the Veterans Health Administration (VHA), for example, have undertaken independent reviews of the evidence, and have developed guidelines that closely resemble the JNC recommendations, with some areas of difference.26, 27

Quality of Care Measures

The recent proliferation of quality measures for the assessment of medical outcomes has spawned multiple measures for particular conditions, including hypertension. Although there is no consensus regarding a single performance measure for determining hypertension quality of care, most national measures have focused on blood pressure control or screening. A multitude of blood pressure measures have been used over the years to assess the quality of care, frequently involving a percentage of patients with blood pressure exceeding a particular control threshold. The Institute of Medicine has stated that control of blood pressure is a valid quality measure, as it has been shown to reduce morbidity and mortality.28 Few report cards have used measures other than blood pressure control or screening to evaluate quality of care (e.g., whether clinicians prescribed one of the recommended first-line antihypertensive medications).

Although blood pressure screening and control have emerged as the consensus choices for hypertension quality metrics, variations on these themes have been developed by different organizations to reflect their particular goals, purposes, or opinions. Developers of quality measures include government agencies, accreditation groups, voluntary health organizations, purchasers, health plans, and physician specialty organizations, among others.22, 2933 Debate regarding the most appropriate measures is ongoing, despite a general agreement that ideal measures should be easy to obtain, reliable, and valid. A selection of the groups involved in the development and/or utilization of hypertension quality measures is described below.

The Agency for Healthcare Research and Quality (AHRQ) commissioned this report and maintains the National Quality Measures Clearinghouse. The Agency is mandated by the U.S. Congress to produce the National Healthcare Quality Report (NHQR), based on available quality measures.29 AHRQ's preliminary quality measures for hypertension include the percentage of people age 21 and over who have had their blood pressure checked within the past two years, and the percentage of people with hypertension who have their blood pressure under control.29

The National Committee for Quality Assurance (NCQA) is the nonprofit accreditation organization that developed and maintains the Health Plan Employer Data and Information Set (HEDIS®), which contains quality performance measures for health care plans.33 HEDIS is the most widely used performance measures set in the managed care industry, and also is used by purchasers of health care, regulators, consumers, and health plans. The current HEDIS quality measure for hypertension is the percentage of patients with hypertension, age 46 to 85, whose blood pressure is controlled (defined as SBP < 140 mmHg and DBP < 90 mmHg). In the year 2000, for example, 51.5 percent of patients participating in managed care plans that reported their HEDIS data had controlled blood pressure.34 This figure represents a significant improvement over the 39 percent result obtained in 1999 for the same HEDIS measure.34 Moreover, the year 2000 percentage is notably higher than the estimated percentage of known hypertensives in the general American population whose blood pressure is under control.34

The Veterans Health Administration (VHA) utilizes quality measures to evaluate hypertension care within its delivery system. These measures include the percentage of patients with an active diagnosis of hypertension whose most recent blood pressure recording was less than 140/90 mmHg, and the percentage of patients with an active diagnosis of hypertension whose most recent blood pressure reading was ≥ 160/100 mmHg, or for whom no blood pressure had been recorded during the previous year.35

Key Questions

There are several important questions that warrant consideration in the realm of hypertension quality improvement. Some of these questions focus on prevention (screening) while others relate to the management of a chronic disease (blood pressure control). The reviewers have selected the following questions as important foci in the development of this report:

  • Which QI strategies improve the process of screening for hypertension?
  • Which QI strategies most effectively ensure that blood pressure goals are achieved and maintained?
  • Which QI strategies improve provider adherence to recommended guidelines for hypertension management?
  • Which QI strategies improve patient adherence to hypertension treatment?

Several features of hypertension pose challenges to the development and evaluation of quality improvement strategies. First and foremost, hypertension is generally asymptomatic; individuals afflicted with hypertension typically do not feel any differently from those who do not suffer the condition. In addition, medical treatment for hypertension may cause adverse side effects. These factors may make patients less likely to adhere to treatment. Additionally, hypertension is most often a chronic condition, requiring lifelong management. Patients whose blood pressure is controlled at one point in time may discover it is not well controlled at another time. This dilemma may present a challenge to those designing studies to evaluate the impact of QI interventions.

In addition, treatment must be individualized for each patient. While the different classes of antihypertensives are effective in lowering blood pressure on a population basis, any individual patient may be more or less responsive to a particular medication, and/or may develop particular adverse effects. If a patient's blood pressure already is well controlled through the use of a particular drug, changing to a different drug carries with it a possibility that the new drug will yield no benefit. The patient also could develop a drug-related adverse effect, requiring dose titration or other changes to the treatment regimen. Orthostatic hypotension is another concern, particularly in older adults with diminished autonomic responses to maintain blood pressure in the standing position. Many patients will require two, three, or more antihypertensive drugs to achieve the target blood pressure. Generally speaking, patients with hypertension tend to be older and often have other medical disorders requiring drug treatment. This patient population must be monitored closely for adverse drug effects and/or drug-drug interactions. Changing guideline recommendations and the wide variety of available therapies present further challenges to QI development and evaluation, given the dynamic nature of physician knowledge and patient knowledge concerning hypertension.



National Heart, Lung, and Blood Institute, American Academy of Family Physicians, American Academy of Insurance Medicine, American Academy of Neurology, American Academy of Ophthalmology, American Academy of Physician Assistants, American Association of Occupational Health Nurses, American College of Cardiology, American College of Chest Physicians, American College of Occupational and Environmental Medicine, American College of Physicians - American Society of Internal Medicine, American College of Preventive Medicine, American Dental Association, American Diabetes Association, American Dietetic Association, American Heart Association, American Hospital Association, American Medical Association, American Nurses Association, American Optometric Association, American Osteopathic Association, American Pharmaceutical Association, American Podiatric Medical Association, American Public Health Association, American Red Cross, American Society of Health-System Pharmacists, American Society of Hypertension, American Society of Nephrology, Association of Black Cardiologists, Citizens for Public Action on High Blood Pressure and Cholesterol, Inc., Hypertension Education Foundation, International Society on Hypertension in Blacks, National Black Nurses Association, Inc., National Hypertension Association, Inc., National Kidney Foundation, Inc., National Medical Association, National Optometric Association, National Stroke Association, NHLBI Ad Hoc Committee on Minority Populations, Society of Geriatric Cardiology, Society for Nutrition Education, Federal Agency Representatives, Agency for Healthcare Research and Quality, Centers for Medicare and Medicaid Services, Department of Veterans Affairs, Health Resources and Services Administration, National Center for Health Statistics, National Institute of Diabetes and Digestive and Kidney Diseases

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