Strategies for Improving Blood Pressure Control

Despite our growing awareness and understanding of clinical hypertension, the outcomes of treating this common condition remain disappointing. The most obvious short-term outcome is blood pressure itself. According to the Third National Health and Nutrition Examination Survey (NHANES 3),1 barely one-quarter of hypertensive patients in the United States have achieved a blood pressure < 140/90 mm Hg. This high failure rate comes as the Joint National Committee on the Detection, Evaluation and Treatment of High Blood Pressure (JNC VI)2 has contemplated epidemiologic data indicating that blood pressure values of 140/90 mm Hg—which previously had been considered an acceptable target for antihypertensive therapy—might carry an excessive risk of cardiovascular events. Indeed, the newest blood pressure classification of the JNC considers 130–139 mm Hg systolic and 85–89 mm Hg diastolic to be “high normal,” and makes the point that ≤ 120/80 mm Hg is optimal. Only a small fraction of hypertensive patients ever have their blood pressures reduced to normal (< 130/85 mm Hg). Of course, blood pressure control is not the full story. We now realize that hypertension is a syndrome of metabolic and cardiovascular abnormalities,3 and that protection of patients from coronary episodes and other clinical events requires more intervention than simply reducing blood pressure. Nevertheless, achieving effective blood pressure control remains a daunting challenge. A variety of clinical, behavioral, economic, and logistical factors may help explain why hypertension treatment has not been more effective. Some of the principal factors are listed in Table 1. Traditionally, because hypertension typically is asymptomatic, many individuals with hypertension were not identified. Lack of a diagnosis has become less of an explanation for poor control of blood pressure as public awareness campaigns—aided by community screening and the fact that most young people need at least perfunctory physical examinations to enter schools, participate in sports, or purchase insurance—have enabled most people to know their blood pressure status. Reasons for Poor Blood Pressure Control Reasons for Poor Blood Pressure Control At any given time, up to half of all hypertensive patients are not receiving treatment.4 This is partly because some individuals, perhaps because of adverse employment or financial circumstances, do not have access to health care. More commonly, though, the absence of therapy comes from a failure of patients to adhere to their treatment regimens. The reasons for this lack of treatment compliance are not clear. Adverse effects of drugs sometimes have been blamed, but this is relatively uncommon with modern antihypertensive agents. The costs of drugs and other aspects of hypertension management have been cited. But there is little evidence that compliance with treatment is improved when patients have access to cost-free services at Veterans Affairs medical centers, health maintenance organizations, or free clinics. More likely, treatment failure results from a decision by the patient, consciously or unconsciously, to drop out of therapy. Behavioral scientists have not yet explained this phenomenon. The failure of so many patients to follow their programs reflects a communications failure by health professionals. Results are not always ideal even when patients take their medications. Physicians can be too easily satisfied with modest blood pressure reductions and do not make necessary adjustments in treatment to optimize results. In a recent large-scale community-based hypertension clinical trial, for example, the on-treatment diastolic blood pressures of patients selected for the study were in the mid 90s.5 Clearly, many clinicians selected to join the trial had not yet responded to the recommendations of the JNC. In fairness, blood pressure is often difficult to control. Patients do not always exhibit satisfactory responses to appropriately selected drugs, even when given in logical combinations. Despite the many antihypertensive agents now on the market, physicians still need additional therapeutic tools. Understanding the major causes for poor blood pressure control provides a basis for strategies that can address this problem. These approaches are discussed below and are listed in Table 2. Strategies for Improving Blood Pressure Control Strategies for Improving Blood Pressure Control Clinicians, even those regarded as experts in hypertension, have not been very successful in improving patient compliance with antihypertensive treatment. It is difficult, if not impossible, to attain good blood pressure control in patients who rarely keep appointments or dropout of treatment completely. One group of patients with reasonably good results are those who participate in formal clinical trials. They are motivated by a sense of loyalty or by an implied contract with the individuals who care for them. This care is often not provided by physicians, but by nurses or other trained personnel. Patients also appreciate the relatively frequent visits required by clinical trials, perhaps responding to this solicitous and committed approach. It is possible that frequent visits, facilitated by dedicated nonphysician professionals, could provide a partial solution to the problem of poor compliance among hypertensive patients. Busy physicians are often irritated when antihypertensive drugs produce side effects or complaints from patients. Similarly, as the goals of treating hypertension have expanded to include the management of such common concomitant conditions as lipid disorders, physicians are finding this commitment to be more burdensome. This may explain why many physicians accept less than ideal blood pressure control if patients do not express complaints and if routine laboratory tests are satisfactory. Clinicians may not be aware of the newer, more stringent guidelines for controlling blood pressure discussed earlier. There is clearly now a need for teaching resources to reemphasize the importance of achieving these goals. It will be interesting to see whether the growing scrutiny of physician performance by managed care organizations will affect blood pressure control. As these organizations undertake to improve their own adherence to public hypertension guidelines they are likely to use the threat or reality of chart audits to compel physicians to follow more aggressive treatment strategies. Selection of drugs for treating hypertension should not be empirical. Rather, there can be good reasons for choosing drugs. One such approach is the use of renin profiling; in general, higher renin levels tend to predict good therapeutic responses to such agents as ACE inhibitors and β-blockers, whereas low renin levels tend to predict good responses to diuretics or calcium channel blockers.6 The age and ethnic origins of patients can help. ACE inhibitors and β-blockers appear to be effective in younger age groups and white patients, whereas diuretic and calcium channel blockers are especially useful in middle-aged or older age groups and in black patients. Single-agent therapy, or monotherapy, even in full doses, normalizes blood pressure in < 50% of hypertensive patients. This may indicate that hypertension is multifactorial in origin and requires more than one type of intervention, or it may reflect powerful compensatory factors in response to the initial treatment. The antihypertensive efficacy of diuretics is often weakened by reactive stimulation of the renin-angiotensin system. Adding an ACE inhibitor or a β-blocker improves blood pressure control.7 Thoughtful combination therapy also allows the use of relatively low dosages of each of the component drugs, thereby minimizing the potential for side effects.8 Newer types of combinations, including those comprised of calcium channel blockers with either ACE inhibitors or β-blockers, appear to have powerful antihypertensive effects. Even the most skillful physician working with highly motivated patients cannot always achieve optimal blood pressure results. Such newer drug classes as calcium channel blockers, ACE inhibitors, and angiotensin receptor blockers have been useful additions to the armamentarium, particularly as they generally produce only minimal side effects. The angiotensin receptor blockers are indistinguishable from placebo in their adverse effect profiles. But therapeutic challenges still remain, and physicians will await with interest the development of such innovative compounds as neutral endopeptidase inhibitors or agents that inhibit endothelin activity or enhance nitric oxide mechanisms. Several factors explain the disappointing overall results of treating hypertension. The single greatest challenge lies in motivating patients to adhere to treatment. Physicians, too, must be encouraged to find ways to ensure that their patients continue treatment and receive the benefits of newer, more aggressive strategies for controlling blood pressure. This will require as much input from behavioral experts as from clinicians and scientists.