Understanding Uncontrolled Hypertension

The management of hypertension has been a major public health success in the United States, and large integrated healthcare systems now achieve control to less than 140/90 mm Hg in 80% of their hypertension patients.1, 2 This was achieved through rigorous programs that included creation of disease registries, audit and feedback on performance, and use of physician extenders. While some older studies suggested that hypertension control rates in Western Europe were lagging compared with those in the United States,3 more recent data from Germany, including an article by Sarganas and Neuhauser,4 published in this issue of the Journal of Clinical Hypertension, suggest that the control rate there among treated patients is now also over 70%. Faced with such high control rates, is it now time to claim success in hypertension care, or are new research and quality-improvement efforts required to further enhance control rates? To answer this question, we must be aware of where we are in understanding uncontrolled hypertension. We certainly have come a long way in our understanding of this problem. In 1988, when the Fourth Report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure was published,5 uncontrolled hypertension was largely viewed as a problem of poor adherence with the failure of patients to follow recommended therapies as “the major reason for inadequate control of high blood pressure.” Since then, there have been a large number of research studies that have resulted in a more nuanced understanding of uncontrolled hypertension. In particular, the central role of clinicians and their reluctance to intensify therapy, referred to as clinical inertia, has been identified as a leading cause of uncontrolled hypertension.6, 7 Clinical inertia is measurable and has repeatedly been shown to be associated with poor blood pressure (BP) control.8, 9 In comparing their relative contributions, studies have generally found that the failure to intensify therapy may play a larger role in uncontrolled hypertension than medication nonadherence.10-12 Access to healthcare is necessary for hypertension control. In the Rand Health Insurance Experiment, participants randomized to free care had lower BP rates and better adherence to quality of care criteria than patients who paid for part of their care.13 Yet, even in the United States, where many people prior to the passage of the Affordable Care Act lacked healthcare insurance, most uncontrolled hypertension occurs “under the watchful eye of the health care system.14” Based on the National Health and Nutrition Examination Survey, 92% of people with uncontrolled hypertension have health insurance, 86% have a usual source of care, and the mean number of visits per year to a physician for patients with uncontrolled hypertension was 4.28.14 One would expect that access to healthcare would not be an issue for hypertension patients in most Western European countries and not a major explanation for uncontrolled hypertension. Characteristics of patients with uncontrolled hypertension have also been consistently identified in studies going back more than 20 years. These factors include older age, black race, having diabetes, being obese, and having increased creatinine.15, 16 Sarganus and Neuhauser also examined factors associated with apparent resistant hypertension in Germany.4 These same factors, excluding race, which was not evaluated, were identified as being associated with apparent resistant hypertension among German hypertension patients.4 The fact that not all of these characteristics achieved statistical significance on multivariate testing might be explained by the relatively small numbers of people with resistant hypertension in this sample. This highlights the common challenge, and opportunities for learning, that confront clinicians in both the United States and Germany. Interestingly, the causes of uncontrolled hypertension seem to vary among hypertension patients with these different characteristics. Clinical inertia seems to be particularly common among hypertension patients with diabetes, and the failure to intensify therapy is more common than in patients without diabetes with similar BPs.10, 17, 18 This could be explained by competing demands in which clinicians invest considerable time and effort into managing glycemic control rather than BP control. Efforts focused on assisting clinicians’ management of these common conditions might then be the key to improvement. In contrast, studies suggest that among black patients with uncontrolled hypertension, treatment intensification is equally or more likely when compared with white patients.19 Rather than focusing on clinical inertia, community-based support through influential peers can promote healthier behaviors and improved hypertension control in this population.20 Uncontrolled hypertension in obese patients might be caused by obstructive sleep apnea, suggesting that different interventions will be needed to achieve control in these patients.21 This suggests that further improvements in hypertension control rates will indeed be possible, both in this country and in Germany. However, the above data suggest that uncontrolled hypertension can no longer be considered to have a single cause. As a result, we cannot expect that one-size-fit-all interventions, which have contributed to the current success, will lead to substantial further improvements in control rates at already high-performing integrated healthcare systems. Instead, further improvement efforts will need to be tailored to the unique barriers for specific subpopulations. This will require considerable effort on the part of clinicians, both to understand why hypertension control is not being achieved in individual patients and in determining how best to improve control in these smaller subpopulations. The recently completed Systolic Blood Pressure Intervention Trial (SPRINT)22 will pose additional challenges to achieving hypertension control. While national guideline committees will need to develop new recommendations for treatment targets, they certainly will be set well below 140 mm Hg for systolic BP. Avoiding the harms of overtreatment while striving to reach this new goal will also be a challenge.23 It is likely that many of the same programs that proved so successful in achieving control at the 140 mm Hg level will work for this lower threshold. We can also expect that the same patient characteristics associated with poor control at 140 mm Hg will be associated with poor control at this lower threshold. Tailored interventions addressing uncontrolled hypertension patients will still need to be developed if we are to extend the benefits of treatment to as many people as possible. While the hypertension community has much to be proud of, there still is a long way to go. This material is the result of work supported with resources and the use of facilities at the Edith Nourse Rogers Memorial VA Medical Center, Bedford, MA. Dr Berlowitz reports no conflicts of interest.