The American Society of Hypertension and the International Society of Hypertension Guidelines for Hypertension Management: An In-Depth Guide

New hypertension guidelines from the American Society of Hypertension and the International Society of Hypertension differ from the JNC 8 guidelines on several key points.

The American Society of Hypertension (ASH) and the International Society of Hypertension (ISH) have issued clinical practice guidelines for management of hypertension in the community. These guidelines differ from those recently issued by the Eigth Joint National Committee (JNC 8) panel, which are undergoing a review and are not yet the national standard.

The guideline panel, headed by lead author Michael A. Weber, MD, created the hypertension guidelines with the goal of enabling, “health care practitioners, wherever they are located, to provide professional care for people with hypertension.”

The importance of blood pressure control is well documented. High blood pressure is known to increase the risk of cardiovascular events, stroke, and kidney disease. As blood pressure rises above 115/75 mm Hg, each 20-mm Hg increase in systolic blood pressure or 10-mm Hg increase in diastolic blood pressure doubles the risk of stroke or other major cardiovascular events.

Importantly, hypertension may place patients of African ancestry at higher risk than other groups of patients. In patients of African ancestry, elevated blood pressure is 3 to 5 times more likely to cause renal complications than an equal elevation in blood pressure among patients of Caucasian descent. In addition, patients of African ancestry may be more sensitive to dietary salt intake, and may not respond as well to treatment with angiotensin-converting enzyme inhibitors (ACEIs), angiotensin receptor blockers (ARBs), or beta-blockers.

The panel defined hypertension in need of pharmacologic treatment by the newest treatment cutoffs. Among adults aged 18 to 79 years, a systolic blood pressure ≥140 mm Hg and/or a diastolic blood pressure level ≥90 mm Hg that persists through repeated testing may indicate a need for pharmacologic treatment. However, in patients over the age of 80 years, systolic blood pressure levels must exceed 150 mm Hg before a diagnosis may be confirmed, which partly agrees with the JNC 8 guidelines (in JNC 8, the 150 mm Hg systolic blood pressure cutoff starts at the age of 60 years).

However, unlike the JNC 8 panel, the ASH/ISH panel continues to advocate separation of hypertension into stage-1 and -2 categories, with stage 1 hypertension classified as a level 140-159/90-99 mm Hg and stage 2 hypertension classified as ≥160/≥100 mm Hg. In both cases, an elevation of either systolic or diastolic readings constitutes hypertension that may require treatment.

Causes of hypertension are not fully known, but environmental factors such as high salt intake, obesity, and a sedentary lifestyle may contribute to its development. In addition, some genetic risk factors may be at work. Although some cases of hypertension may be treated through correction of intrinsic causative factors (such as pheochromocytoma, sleep apnea, renal artery stenosis, or kidney disease), hypertension due to these causative factors accounts for fewer than 5% of all cases of hypertension. Despite the rarity of hypertension with a correctable root cause, the draft ASH/ISH guidelines recommend screening for these intrinsic causative factors in some patients.

Blood Pressure Measurement and Patient Assessment

The ASH/ISH panel recommends against use of wrist cuffs for measurement of blood pressure as arm cuffs tend to provide more accurate measurements. However, when the arm cuff is used in patients in patients whose arms exceed 32 cm in circumference, a wider cuff should be used to prevent misreading. At minimum, 2 blood pressure readings should be taken, with the second measure occurring least 1 to 2 minutes after the first, and the results should be averaged. Blood pressure readings taken when standing may useful with older patients to check for postural hypotension. In addition, ambulatory monitoring over a 24-hour period may be an option in some patients.

Assessment of patients under the ASH/ISH guidelines involves more than obtaining blood pressure readings. It also involves assessment of a patient's history, including whether or not the patient has received a diagnosis of hypertension in the past, and assessment for many other factors including a history of:

• Stroke or transient ischemic attack
• Coronary artery disease, myocardial infarction, or acute coronary syndrome
• Heart failure symptoms
• Chronic kidney disease
• Peripheral artery disease
• Diabetes
• Sleep apnea
• Cigarette smoking
• Use of medications that may exacerbate hypertension (high-dose pseudoephedrine, antidepressants, high-dose oral contraceptives, migraine medications, recreational drugs, or nonsteroidal anti-inflammatory drugs)

Patients may also be assessed for cardiovascular risk through:

• Assessment of the patient's body mass index, waist circumference (a circumference >102 cm in men or >88 cm in women indicates high cardiovascular risk)
• Neurologic examination
• An eye examination
• Peripheral pulses (which can help detect peripheral artery disease)

The panel also recommends:

• Electrolyte testing
• Assessment of fasting glucose levels
• Serum creatinine and blood urea nitrogen level testing
• LDL cholesterol level testing
• Hemoglobin/hematocrit level testing
• Liver function testing
• Testing for albuminuria
• Electrocardiography

Like the JNC 8 guidelines, guidelines from the ASH/ISH recommend <140/90 mm Hg treatment target in patients with chronic kidney disease, however, the guidelines note that in some patients, particularly in patients with albuminuria, the older <130/80 mm Hg target may be retained.

The ASH/ISH guidelines emphasize the importance of diastolic blood pressure control (<90 mm Hg) in patients under the age of 50 years. As treatment, guidelines recommend weight loss and lifestyle change, including limiting salt intake by avoiding food such as bread, canned goods, fast foods, pickles, soups, and processed meats. Quitting smoking, limiting alcohol intake to 2 drinks daily or fewer in men and 1 drink daily or fewer in women, and adopting a regimen of aerobic exercise may also help control blood pressure. However, in most patients, the guidelines clarify that lifestyle changes are primarily a supplement to pharmacologic therapy—not a replacement.

Initiation of a single pharmacologic agent may begin in patients with a blood pressure level >140/90 mm Hg, and (optionally) a 2-drug combination may be used as a first-line agent in patients with a blood pressure level ≥160/100 mm Hg. After an adequate 2- to 3-week trial of the initial therapy, other agents may be added or the dose of agents may be increased if the first medication fails to control blood pressure.

Like the JNC 8 guidelines, the ASH/ISH guidelines recommend first-line use of 4 core agents: calcium channel blockers (CCBs), ACEIs, ARBS, or thiazides/thiazide-like diuretics. However, unlike the JNC 8 guidelines, the ASH/ISH guidelines recommend certain pharmacologic agents for various subpopulations.

For instance, in patients of African ancestry and in patients aged ≥60 years with stage I hypertension, the preferred first-line agent is a CCB or a thiazide/thiazide-like diuretic. However, in patients <60 years who are not of African ancestry, the first-line agent is an ACEI or an ARB.

Patients with stage 2 hypertension receive a 2-drug combination as the first-line therapy under the ASH/ISH guidelines. Recommended combinations include CCBs plus ARBs and thiazides plus ACEIs.

For patients in need of 2- and 3-drug combinations to control high blood pressure, CCBs, thiazides, and either ACEIs or ARBs may be used, but ACEIs and ARBs should not be used together. Four- and 5-drug combinations may require the addition of miscellaneous agents including spironolactone, clonidine, and beta-blockers.

Special considerations apply to patients with hypertension and diabetes, chronic kidney disease, coronary artery disease, heart failure, or a history of stroke.

• Patients with hypertension and diabetes may start treatment with an ACEI or ARB, although patients of African ancestry may alternatively receive a CCB or thiazide
• Patients with chronic kidney disease may start treatment with an ACEI or ARB
• Patients with coronary artery disease should receive a beta-blocker with either an ACEI or an ARB as initial therapy
• Patients with a history of stroke may start treatment with an ACEI or ARB
• Patients with heart failure should receive an ARB or ACEI with a beta-blocker, a diuretic, and spironolactone. If additional blood pressure control is required, a dihydropyridine CCB may be added

Conclusion

In general the ASH/ISH guidelines agree with the JNC 8 blood pressure guidelines and are very similar. Both guidelines recommend combinations of CCBs, ACEIs/ARBs, and thiazide diuretics as initial therapy for most patients. However, the following are a few key differences between the guidelines:

• The ASH/ISH guidelines retain the stage 1 and stage 2 designations of blood pressure levels and a 2-drug combination tablet is recommended in initial therapy of patients with stage II hypertension
• Potential intrinsic causes of hypertension should be assessed, including pheochromocytoma, sleep apnea, renal artery stenosis, or kidney disease
• The 150 mm Hg systolic blood pressure treatment target begins at the age of 80 years, not 60 years as recommended by JNC 8
• Beta-blockers are recommended as part of initial therapy in patients with coronary artery disease and heart failure
• The <130/80 mm Hg blood pressure treatment goal may still be used in some patients with kidney disease and albuminuria, although the ASH/ISH guidelines are flexible on this topic