Apparent resistant hypertension in sub‐Saharan Africa: Frequency and associated factors
Year: 2020
Type: article
Abstract: Hypertension, defined as a systolic blood pressure greater than or equal to 140 mm Hg or a diastolic blood pressure of greater than or equal to 90 mm Hg, is a major risk factor for cardiovascular disease and the number one cause of global mortality. It is estimated that hypertension causes 7.5 million global deaths annually1 and significantly affects global health care expenditures. The global prevalence of hypertension is estimated to be as high as 30% representing approximately 1.13 billion individuals.2, 3 Unfortunately, the prevalence of hypertension is increasing dramatically, further worsening the global cardiovascular disease burden. Left undiagnosed, untreated, or uncontrolled, hypertension contributes to cardiac disease (coronary artery disease, myocardial infarction, heart failure, left ventricular hypertrophy, and arrhythmia), stroke, renal disease (end-stage or insufficiency), peripheral vascular disease, and vision impairment. Although hypertensive pharmacologic treatment is safe, effective, available, and affordable, present hypertension control rates globally are dismal with fewer than 1 in 5 hypertensive patients controlled with a blood pressure of less than 140/90 mm Hg.2 It is important to note that even in high-income countries, the control rates of hypertension are only approximately 50%-60%.4 Furthermore, 75% of all individuals with hypertension live in low- and middle-income countries4 with 46% of individuals in Africa having hypertension.1 More specifically (and more pertinent to this study), the 2014 Ghana Demographic and Health Survey estimates the overall prevalence of hypertension in Ghana at 13%; 46% of those are aware they have hypertension, 41% are under pharmacologic treatment, and only 24% are controlled.5 Clearly, the present approach to the detection, management, and treatment of hypertension is less than optimal and the planning and implementation of new effective strategies is imperative. One such strategy may be to target individuals with apparent or true resistant hypertension to improve hypertension control rates and reduce the overall burden of the disease. True resistant hypertension is defined as above-goal blood pressure, typically equal to or greater than 140/90 mm Hg despite the use of three complementary antihypertensive medication classes of which one must be a diuretic and all medications must be at maximal doses. True resistant hypertension also includes patients with controlled blood pressures on four or more appropriate antihypertensive medications. The diagnosis of resistant hypertension requires maximum or maximally tolerated medication doses, assurance of medication adherence, and exclusion of the white-coat hypertensive effect.6 If doses are unknown or inadequate, medication adherence is questionable, or out-of-office blood pressure measurements to rule out a white-coat effect are not available, then the term apparent resistant hypertension has been adopted.7 It is important to differentiate those with true resistant hypertension from those with apparent resistant hypertension because the approaches to management and treatment of each are different. In this issue of the journal, Ayisi-Boateng and colleagues in their manuscript entitled “Frequency and factors associated with apparent resistant hypertension among Ghanaians in a multicenter study” report on the frequency and factors associated with apparent resistant hypertension in Ghana. They enrolled 2912 adults diagnosed with hypertension across five differing health facilities. To measure blood pressure, the investigators used the average of two consecutive blood pressure measurements determined by an automated, oscillometric device, taken 2 minutes apart, and after resting for 5 minutes while sitting in a chair with both feet flat on the floor and both arms supported and at the level of the heart. They also recorded demographic data, medical history, and body mass index. To assess medication adherence, the investigators used the Hill-Bone Compliance to High Blood Pressure Therapy Scale, a questionnaire primarily designed to assess medication adherence.8 Ayisi-Boateng and colleagues identified 550 out of 2912 (18.9%) individuals who met the definition of apparent resistant hypertension. These individuals were less likely to reside in a rural setting, have attained a secondary level of education, have had a longer duration of hypertension, and have a lower glomerular filtration rate. Interestingly, they were also less likely to have concurrent diabetes mellitus and use less added table salt in their meals and more likely to consume more fruit than those without apparent resistant hypertension. Body mass index and waist circumference were also significantly greater in those with apparent resistant hypertension than those without. Additionally, the scores on the adherence questionnaire were comparable between those with and without apparent resistant hypertension at approximately 18 (perfect score = 14). The most frequently used antihypertensive medication class in both the apparent resistant hypertension group as well as the group without apparent resistant hypertension was calcium channel blockers.9 The study identified living in urban communities as significant risk factors for apparent resistant hypertension. This is consistent with the explanation that one of the reasons that hypertension is increasing in low- to middle-income countries, including in sub-Saharan Africa, is due to the migration of the population from rural to urban areas. Urban living is associated with less physical activity, higher intake of salt and fatty foods (“westernized diet”), more alcohol and tobacco use, and increased stress, all of which alone or in combination can increase the prevalence and severity of hypertension and cardiovascular disease. Interestingly, once the investigators adjusted for confounding factors, the association between urban location and hypertension was not statistically significant. The authors highlight the relationship between apparent resistant hypertension and chronic kidney disease, noting a 73% higher adjusted risk of apparent resistant hypertension in patients with estimated glomerular filtration rates below 60 mL/min per 1.73 m2. Although it is well known that hypertension leads to chronic kidney disease and chronic kidney disease can further increase blood pressure and complicate blood pressure control, appropriate detection and management of chronic kidney disease in low- to middle-income countries are disproportionately problematic. The majority (80%) of the nearly 500 million people with chronic kidney disease worldwide live in low- to middle-income countries.10 To further complicate this issue, epidemiological data in these countries can be poorly characterized due to non-standardized approaches, inconsistent assessments, and lack of community-based studies.10 Thus, this study underscores the necessity of a broad, cross-disciplinary public health response to detect and reduce the morbidity and mortality associated with chronic kidney disease, in addition to hypertension. This manuscript addresses a growing, timely, and important topic: the factors and the frequency of these factors associated with apparent resistant hypertension in Ghana. This study is of particular importance as we have little data on hypertension from sub-Saharan Africa, and the morbidity and mortality from cardiovascular disease are projected to increase significantly in this region in the coming decades.11 This paper serves to heighten awareness of this growing problem and adds to the literature regarding hypertension in low- and middle-income countries. In addition, these authors were able to gather data from almost 3000 individuals in an array of different patient settings. Such research provides crucial information needed to develop and implement new strategies and programs to detect, manage, and treat hypertension with the overall goal of increasing the control rates of hypertension in areas such as Ghana. A potential limitation of this study is that the authors could not determine the etiology or etiologies of the apparent resistant hypertension, potentially limiting the generalizability of these findings and specific clinical treatment modalities. One probable etiology of the apparent resistant hypertension could simply be under treatment by either not using appropriate complementary classes of medications, not appropriately dosing specific medications, or a combination of both. Since the doses and the exact combinations of medications are unknown, it is possible that what the authors label as apparent resistant hypertension could simply be under treatment. Another possible etiology of the apparent resistant hypertension could be nonadherence. The authors did assess adherence with a self-reported questionnaire, however, as with all such questionnaires, there could be recall bias. The authors recognize the importance of exploring areas of future research and clinical programs. One possibility is a population-based, public health, and primary care approach to the detection and treatment of hypertension. Such an approach involves a large degree of structure, standardize care, the establishment of a small and simple hypertension pharmacologic formulary, and the use of straightforward medication treatment algorithms/protocols. In such a program, care is team based and includes support, registries, and feedback to clinics and individual providers. For example, the Global HEARTS Initiative of the World Health Organization has produced a HEARTS Technical Package which consists of six individual modules which supports this approach. Similar models have demonstrated significant success with communicable diseases such as tuberculosis and HIV, and previously designed programs implemented for the detection and treatment of hypertension in low- to middle-income countries have rapidly increased hypertension control rates.12 In summary, hypertension and cardiovascular disease morbidity and mortality are a growing global “pandemic” that is especially adversely affecting low- to middle-income countries. Given the low control rates of hypertension worldwide, new comprehensive strategies are urgently needed to address this “pandemic.” There clearly are unique challenges in low- and middle-income countries which present barriers to the detection and control of hypertension which complicate any recommendations. One complication is the lack or minimal availability of quality and broad population-based data regarding hypertension that is actionable. The study in this issue detailing the frequency and factors association with apparent resistant hypertension in Ghanaians provides such data. It is hoped that data such as reported in this study will spur future investigations and changes in detection and treatment strategies of hypertension. Donald J. DiPette is a Distinguished Health Sciences Professor, University of South Carolina and University of South Carolina School of Medicine, Columbia, South Carolina, USA. None to report.
Source: Journal of Clinical Hypertension
DOI: 10.1111/jch.13970
Institution: University of South Carolina
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W3047672308