Therapy of Hypertension in African Americans

Abstract and Introduction

Abstract

Hypertension in African Americans is a major clinical and public health problem because of the high prevalence and premature onset of elevated blood pressure (BP) as well as the high burden of co-morbid factors that lead to pharmacological treatment resistance (obesity, diabetes mellitus, depressed glomerular filtration rate, and albuminuria). BP control rates are lower in African Americans, especially men, than in other major race/ethnicity-sex groups; overall control rates are 29.9%for non-Hispanic Black men. Optimal antihypertensive treatment requires a comprehensive approach that encompasses multifactorial lifestyle modifications (weight loss, salt and alcohol restriction, and increased physical activity) plus drug therapy. The most important initial step in the evaluation of patients with elevated BP is to appropriately risk stratify them to allow determination of whether they are truly hypertensive and also to determine their goal BP levels. The overwhelming majority of African American hypertensive patients will require combination anti-hypertensive drug therapy to maintain BP consistently below target levels. The emphasis is now appropriately on utilizing the most effective drug combinations for the control of BP and protection of target-organs in this high-risk population. When BP is >15/10 mmHg above goal levels, combination drug therapy is recommended. The preferred combination is a calcium antagonist/angiotensin-converting enzyme inhibitor or, alternatively, in edematous and/or volume overload states, a thiazide diuretic/angiotensin-converting inhibitor.

Introduction

Hypertension in African Americans is a major clinical and public health problem because of the high prevalence and premature onset of elevated blood pressure (BP) in this population.^[1] Moreover, the common occurrence of pressure-related target-organ injury (e.g. left ventricular hypertrophy, heart failure) and the high prevalence of risk-augmenting co-morbidities such as diabetes mellitus and chronic kidney disease in African Americans markedly increase the likelihood of pressure-related morbidity and mortality in this group at any given BP level.^[2] These issues result in the long-term exposure of large proportions of African Americans to higher than optimal BP and disproportionate development of associated consequences.

BP control rates are lower in African Americans, especially men, than in other major race/ethnicity-sex groups; overall control rates are 29.9% for non-Hispanic Black men.^[3] Even amongst drug-treated African Americans with hypertension, only 45%have been reported to attain BP control.^[4] Hypertension places an exceptionally high toll on the African American population, accounting for approximately 30% and 20% of all deaths, respectively, in African American men and women^[5] and 15% of the overall racial difference in potential life-years lost.^[6] Thus, enhancing BP control rates represents a profoundly important strategy for the improvement of health status and reduction of pressure-related racial health disparities (e.g. heart failure, retinopathy, stroke) that disproportionately afflict the African American population.

Cite this: Therapy of Hypertension in African Americans - Medscape - Apr 01, 2011.

Table I. Comparison of blood pressure risk stratification
Parameter	Risk stratification scheme
Parameter	JNC 7^[26]	ISHIB^[23]
High risk group
Criteria	Diabetes and/or CKD^a	Target-organ damage^b, pre-clinical CVD^c, and/or presence of CVD^d
Goal BP (mmHg)	<130/80	<130/80
Low risk group
Criteria	All other hypertensives	All other hypertensives
Goal BP (mmHg)	<140/90	<135/85

a Estimated glomerular filtration rate <60 mL/min/1.73 m² and/or albumin : creatinine ratio >200mg/g.
b Estimated glomerular filtration rate <60 mL/min/1.73 m², albumin : creatinine ratio >200 mg/g, and/or electrocardiographic or echocardiographic evidence of left ventricular hypertrophy.
c Metabolic syndrome, Framingham risk score >20%, pre-diabetes mellitus (impaired fasting glucose [100–125 mg/dL] and/or impaired glucose tolerance [2-hour post glucose load 140–199 mg/dL]) or diabetes.
d Heart failure (systolic or diastolic), coronary heart disease/post-myocardial infarction, peripheral arterial disease, stroke, transient ischemic attack, and/or abdominal aortic aneurysm.
CKD= chronic kidney disease; CVD= cardiovascular disease; ISHIB = International Society on Hypertension in Blacks (ISHIB); JNC 7 = Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.

Table II. Highly effective two-drug antihypertensive drug therapy combinations^[23]
Thiazide or thiazide-like diuretic^a,b plus
RAS antagonist^c
Aldosterone antagonist
Amiloride
β-Adrenoceptor antagonist
Calcium channel antagonist
Calcium channel antagonist plus
RAS antagonist
Thiazide or thiazide-like diuretic
β-Adrenoceptor antagonist
Aldosterone antagonist
Dual calcium channel antagonist blockade
Amlodipine plus a non-dihydropyridine^d calcium channel antagonist

a Hydrochlorothiazide.
b Chlorthalidone.
c ACE inhibitor, angiotensin II type 1 receptor antagonist (angiotensin receptor blocker), or direct renin inhibitor.
d Verapamil or diltiazem.
RAS= renin-angiotensin-aldosterone system

Table III. Relatively ineffective antihypertensive two-drug class combinations^[23a]
ACE inhibitor + ARB
β-Adrenoceptor antagonist + ACE inhibitor or ARB
β-Adrenoceptor antagonist + central adrenergic inhibitor (e.g. clonidine)
α-Adrenoceptor antagonist + central adrenergic inhibitor

a Also, β-adrenoceptor antagonists plus non-dihydropyridine calcium channel antagonists should be avoided because both drugs have negative inotropic and chronotropic effects on the myocardium.
ARB= angiotensin II type 1 receptor antagonist (angiotensin receptor blocker)

Table IV. Recommendations for antihypertensive drugs by co-morbidity
Co-morbidity	ACEI	ARB	Aldo antag	β-Blocker	CCB	Diuretic
CHD/angina	✓	•		✓	✓	•
CKD	✓	✓	Ø^a		•	•
Diabetes mellitus/prediabetes	✓	✓		•	•
Heart failure	✓	✓	✓	✓	Ø^b	•
High vascular disease risk	✓	✓				•
Post-MI	✓	✓	✓	✓
Recurrent stroke prevention	✓	✓				•

a If estimated glomerular filtration rate is <50mL/min/1.73m², eplerenone only; use spironolactone with caution; periodically check serum potassium levels.
b Non-dihydropyridine CCBs (diltiazem, verapamil) are contraindicated in patients with systolic heart failure.
ACEI =ACE inhibitor; Aldo antag = aldosterone antagonist; ARB= angiotensin II type 1 receptor antagonist (angiotensin receptor blocker); CCB= calcium channel antagonist (blocker); CHD= coronary heart disease; CKD= chronic kidney disease; MI = myocardial infarction; ✓ indicates compelling indication (proven benefit); • indicates likely benefit or safety proven; Ø indicates contraindication.

Table V. Recommended diuretic(s) according to the level of kidney function
eGFR (mL/min/1.73 m²)	Single diuretic	Dual diuretics
>45	Chlorthalidone HCTZ	Chlorthalidone or HCTZ plus an aldosterone antagonist or amiloride
30–44	Chlorthalidone Loop diuretic^a Metolazone	Chlorthalidone plus a loop diuretic Metolazone plus a loop diuretic
<30	Loop diuretic Metolazone	Metolazone plus a loop diuretic

a If furosemide is used, dosing should be at least twice daily unless it is being combined with the long-acting thiazide-like diuretic metolazone or chlorthalidone. eGFR= estimated glomerular filtration rate; HCTZ= hydrochlorothiazide.

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