Management of Hypertension

Abstract

High blood pressure (BP) is associated with an increased risk of stroke, coronary heart disease (CHD), heart failure and also an accelerated decline in both cognitive and renal function. As BP increases, so does the likelihood of these complications. In the UK, hypertension still remains undiagnosed and under treated with less than half of treated hypertensives having optimally controlled BP. A reduction of BP by an average of 12 mmHg systolic and 6 mmHg diastolic can be expected to reduce stroke by 40% and CHD by 20% (relative risk reduction).

Hypertension and the GP Curriculum

RCGP Curriculum statement 5: Healthy People suggests that GPs understand the role of prevention and preventative strategies, the principles of health surveillance and have the skills to change patients’ behaviour with health promotion and disease prevention as part of primary care management. Specific problem-solving skills in this domain include a comprehensive assessment of an individual patient's risk factors and an understanding of the broader role of the GP, the wider primary health care team and other health promotion activities within the community.

RCGP Curriculum statement 15.1: Cardiovascular Problems under primary care management states that GPs should manage primary contact with patients who have a cardiovascular problem. They should be able to describe strategies for early detection of cardiovascular problems that may already be present but have not yet produced symptoms. In addition it is important to promote cardiovascular well-being by applying health promotion and disease prevention strategies appropriately. GPs should be able to identify patient health beliefs regarding cardiovascular problems and reinforce, modify or challenge these beliefs as appropriate. It is essential to recognize that non-compliance is common for many preventative cardiovascular medicines and respect the patient's autonomy when negotiating management.

GPs should communicate the patient's risk of cardiovascular problems clearly and effectively in a non-biased manner and utilize disease registers and data-recording templates effectively. This allows for opportunistic and planned monitoring of cardiovascular problems to ensure continuity of care between different health care providers. Clinical skills should include BP measurement, calculation of cardiovascular risk and performing an electrocardiogram (ECG) with basic interpretation.

It is important to recognize that hypertension is one of several risk factors for atherosclerotic disease and is essential that management of BP should encompass management of cardiovascular risk as a whole with an emphasis on lifestyle measures and health promotion. It is beyond the scope of this article to discuss the management of all associated cardiovascular risk factors and purely the management of hypertension alone will be addressed.

Measuring BP

BP should be taken in a seated position, having removed tight clothing and supporting the arm at heart level. Ask the patient to relax the arm and remain quiet during the measurement procedure. A standing BP is not required routinely but should be measured in elderly or diabetic patients to exclude orthostatic hypotension (fall in systolic BP by greater than 20 mmHg) which will influence management.

Devices for measuring BP should be properly validated, maintained and regularly calibrated according to the manufacturers' instructions. Choose an appropriately sized cuff and lower the mercury column at around 2 mm/second taking a reading to the nearest 2 mmHg. Measure diastolic BP at disappearance of sounds (phase V).

Routine use of ambulatory or home BP monitoring in primary care is not currently recommended by National Institute of Clinical Excellence (NICE) but doctors should be wary of treating ‘white coat’ hypertension and consider the use of 24 hour BP monitoring if suspected. White coat hypertension can then be diagnosed in patients with clinic BPs of greater than 140 mmHg systolic or 90 mmHg diastolic but with average daytime ambulatory BP readings of less than 135 mmHg systolic and 85 mmHg diastolic.

Definition of hypertension

The Joint British Societies' guidelines on prevention of cardiovascular disease in clinical practice (Joint British Societies, 2005) state that the pragmatic definition of hypertension is the level of BP at which there is evidence that BP reduction does more good in terms of reducing cardiovascular disease (CVD) risk than harm.

Hypertension is defined as a systolic BP reading in an adult of greater than 140 mmHg and/or a diastolic reading of greater than 90 mmHg. Hypertension can then further be graded as high normal, mild, moderate and severe (Table 1).

Table 1.

Grades of hypertension

	Systolic BP (mmHg)	Diastolic BP (mmHg)
Normal	<120	<80
High normal	135–139	85–89
Mild hypertension (Grade 1)	140–159	90–99
Moderate hypertension (Grade 2)	160–179	100–109
Severe hypertension (Grade 3)	>180	>110

Hypertension cannot be diagnosed on the basis of one reading alone and patients suspected of having raised BP should have several readings under the best available conditions. Ideally, two BP readings should be taken at each of three assessment visits, with assessment visits a month apart. The two readings taken at each visit should be averaged and recorded. If the hypertension is severe, it is appropriate to do the three assessments over the course of a month.

Target organ damage

Evidence of target organ damage should be sought from the history, including past medical history. Tests including bloods to check renal function and for evidence of diabetes, a urine dipstick for proteinuria and an ECG to look for left ventricular hypertrophy may also be helpful. See Box 1 for a detailed list of assessments for end organ damage.

Secondary hypertension

Consider causes of secondary hypertension (Box 2)

in young patients (under 30 years old) with high BP

in patients with abnormal renal function or electrolytes, proteinuria or haematuria or

if hypertension remains uncontrolled on three agents or becomes suddenly worse

Box 1.

End organ damage resulting from hypertension

Past medical history of vascular disease, including coronary heart disease (CHD), stroke or transient ischaemic attack, and peripheral arterial disease

Heart failure

Abnormal renal function either reduced estimated glomerular filtration rate or elevated creatinine or microalbuminuria/proteinuria

Retinopathy—either hypertensive or diabetic

Left ventricular hypertrophy on electro- or echocardiogram

Also consider further investigation of patients with a strong family history of hypertension or cerebrovascular disease under the age of 50 years.

Malignant hypertension and suspected phaeochromocytoma require urgent referral and assessment. Malignant hypertension should be suspected if BP is greater than 180/110 mmHg with signs of papilledema and/or retinal haemorrhages.

Who should we screen for hypertension?

All adults should have BP measured routinely at least every 5 years. If the BP falls into the ‘high normal’ category (systolic of 130–139 mmHg or diastolic BP of 85–89 mmHg) they should then have their BP taken annually according to the British Hypertension Society guidelines. The Joint British Society guidelines suggest that all adults from the age of 40 years should have an opportunistic full CVD risk assessment in primary care. As part of that assessment a BP check should be done. Any patients with known renal disease, diabetes, atherosclerotic disease such as stroke or previous myocardial infarction should also be screened as part of their routine follow-up and ongoing management.

The government's new initiative is for all patients aged 40–74 years to undergo a 5 yearly ‘vascular risk assessment’. The details of this initiative are still in the process of being finalized, however it is likely to involve a more structured risk assessment similar to the current cardiovascular risk assessment. This service will be commissioned by Primary Care Organizations but may be made available by a variety of service providers, not only GPs.

Calculating cardiovascular risk

A cardiovascular risk assessment should be carried out on all patients with high BP to calculate the risk of a cardiovascular event over 10 years. In patients who are already diagnosed as being hypertensive, any pretreatment BP not the BP level achieved on treatment should be used to calculate the overall cardiovascular risk. Most computer systems used in primary care have a tool for assessing and calculating cardiovascular risk along with useful diagrams to use when explaining this concept to patients. Alternatively, risk calculators such as the QRisk2 are available via the Internet.

Box 2.

Secondary causes of hypertension

Drugs

Therapeutic drugs: non-steroidal antiinflammatories, oral contraceptives, steroids, tacrolimus, cyclosporine, erythropoietin, liquorice

Recreational drugs: cocaine, amphetamines

Renal or renovascular disease

Consider in patients with present, past or family history of renal disease, proteinuria or haematuria

On examination look for palpable kidneys or bruit

Endocrine causes

Phaeochromocytoma

Consider if paroxysmal symptoms of hypertension or headache, sweating and palpitations or a family history of multiple endocrine neoplasia

If suspected, check 24 hour urinary catecholamines (sensitivity 86%, specificity 88%)

Conn's syndrome or primary hyperaldosteronism

Consider if tetany, muscle weakness, polyuria, with hypokalaemia

If suspected check plasma aldosterone and renin levels to look for a high ratio of plasma aldosterone to renin concentration. A ratio of greater than 750 is suggestive of primary hyperaldosteronism (although values are laboratory specific and may vary depending on the assays used)

Cushing's syndrome

Consider if typical features on examination, e.g. moon face, centripetal obesity, buffalo hump, hirsuitism, striae, acne, proximal muscle weakness

Other features include recurrent infections, hypokalaemia, osteoporosis and oligomenorrhoea

If suspected, refer to Endocrinology for dexamethasone suppression test

Acromegally

Consider if typical features, e.g. coarse facial features, hand and foot enlargement, overbite of the jaw, splaying of teeth

Also note that acromegally is associated with diabetes, a multinodular goitre, arthropathy and carpal tunnel syndrome

Coarctation

On examination look for radio-radial or radio-femoral delay, or weak femoral pulses

Pregnancy

Management of hypertension

There is no one class of antihypertensive that is any more effective than another at reducing the overall cardiovascular risk in hypertension that requires medication. The benefits come in the quality of BP control, i.e. whichever medication achieves target BP control.

In patients with mild hypertension, over half of the individuals will subsequently fall into the normal range and stabilize over 3–4 months of observation alone. In the patients who continue to have mild hypertension over this period, it is appropriate to monitor them over a period of 3–6 months taking at least four paired readings of BPs. Provided their cardiovascular risk assessment remains less than 20%, and there is no evidence of target organ damage or diabetes, then it is reasonable to offer lifestyle intervention alone, monitor BP and make an annual assessment of cardiovascular risk.

Lifestyle intervention

Recommend lifestyle measures and provide lifestyle advice for all patients with hypertension. This can be used alone for patients with high normal or mild hypertension or together with medication. A quarter of patients receiving lifestyle interventions achieve a reduction of systolic BP of 10 mmHg or more in the first year.

Although stopping smoking does not lower BP, this may be the most important lifestyle intervention to reduce the overall cardiovascular risk. It is therefore worthwhile taking the time to encourage patients to stop smoking and give them support and help through local stop smoking clinics and support groups and by prescribing nicotine replacement therapy or other pharmacological methods such as bupropion or varenicline.

Suggest weight reduction, if appropriate, aiming for a healthy body mass index of 20–25 kg/m². Patients can be motivated with support from weight clinics and should be offered dietary information or dietetic support. A brief summary of dietary advice should focus on a low-salt, low-fat diet with reduced consumption of saturated fat and cholesterol and increased dietary polyunsaturated fat, monosaturated fat and oily fish. Recommend at least five portions of fruit and vegetables per day. The NICE hypertension guideline also discourages excessive caffeine intake as drinking over 5 cups of coffee a day is associated with a small increase in BP.

Recommend alcohol intake of less than 21 U for males and 14 U for females per week. This can be tied in to dietary and weight advice with discussion of the amount of ‘empty’ calories in alcohol.

Encourage exercise tailored to the age and capabilities of the patient. Aim for activity that raises the heart rate for 30–60 minutes three to five times a week. Relaxation therapies such as stress management, meditation, cognitive therapies and muscle relaxation can also reduce BP, but NICE does not recommend routine provision of these services by primary care.

Ideally, all lifestyle recommendations to patients should be backed up with written information and information about guidance and support available locally, such as support groups, dieting clubs or local exercise initiatives. The new ‘Change4Life’ initiative from the Department of Health with its summary of ‘eat less, move more, live longer’ has information on local programmes to tackle obesity, alcohol excess and increase exercise.

When to initiate antihypertensives

Figure 1 summarizes the conditions for initiation of antihypertensive therapy. Antihypertensives should be initiated in patients with a persistently raised systolic BP of over 160 mmHg systolic and/or diastolic BP of over 100 mmHg. For patients with a persistently raised systolic BP of over 140 mmHg and/or diastolic BP of over 90 mmHg, treat only if total cardiovascular risk is over 20% or there is evidence of target organ damage or diabetes. Patients with cardiovascular risk of less than 20% with no evidence of target organ damage or diabetes should continue on lifestyle measures and have BP and CVD risk checked annually.

Figure 1.

Threshold for intervention in management of hypertension.

In patients with a past history of ischaemic heart disease, cerebrovascular disease, renal disease or diabetes, BP management is considered secondary prevention and may be subject to other guidelines. Other co-morbidity and other medications (prescribed or otherwise) should also always be taken into consideration.

Target BP

Target BP will vary according to whether the patient has other co-morbidities. In uncomplicated hypertension, antihypertensives should be titrated to a target BP of less than 140/85 mmHg. NICE guidelines suggest less than 140/90 mmHg, but the Quality and Outcomes Framework (QOF) target is less than 150/90 mmHg (Box 3). This is because the QOF targets are the audit standard, therefore higher. Ideal targets are lower but should be aimed for rather than the QOF standard.

Pharmacological management of hypertension

Most patients with hypertension will not be managed sufficiently on monotherapy alone and combinations of antihypertensives will be required. For this reason, the British Hypertension Society initially advised the Ace inhibitor or Beta-Blocker versus Calcium chanel blocker or Diuretic (AB/CD) algorithm, later to be reviewed by NICE into the recommended Ace inhibitor versus Calcium chanel blocker or Diuretic (A/CD) algorithm. This uses age and ethnicity to decide on initial management, subsequently introducing agents of different classes. There may, however, be a compelling argument or contraindication for certain medications that the doctor should take into account when prescribing for specific groups of patients or patients with other conditions. Table 2 lists these important considerations when initiating therapy. When there are no special considerations, initial drug selection should follow the A/CD algorithm.

Table 2.

Drug indications, cautions and contraindications

	Compelling indication	Possible indication	Caution	Contraindication
ACE inhibitors	Heart failure or ventricular dysfunction, type 1 diabetes with nephropathy, myocardial infarction or angina, previous stroke	Proteinuria and non-diabetic nephropathy, chronic renal disease (with caution), type 2 diabetic nephropathy	Renal impairment, peripherovascular disease (due to association with renovascular disease)	Pregnancy, renovascular disease, hyperkalaemia
ARBs	Cough on ACE inhibitor, left ventricular hypertrophy, heart failure intolerant of ACE inhibitor, type 2 diabetic nephropathy		Renal impairment	Pregnancy, renovascular disease, hyperkalaemia
β-Blocker	Symptomatic angina, post-myocardial infarction, tachyarrhythmia	Pregnancy, patients with evidence of increased sympathetic drive	Heart failure	Asthma/chronic obstructive pulmonary disease, heart block
Calcium channel blockers	Elderly with isolated systolic hypertension, Raynauds syndrome	Elderly with angina	Tachyarrythmias, congestive cardiac failure, combination with β-blocker (if rate limiting)	Heart block, heart failure
Thiazides	Elderly, including isolated systolic hypertension, hypertensives of African ethnicity, heart failure, previous stroke		Pregnancy	Gout
Diuretics (anti-aldosterone)	Heart failure, post-myocardial infarction			Renal failure, hyperkalaemia
α-Blocker	Benign prostatic hypertrophy, hyperlipidaemia		Orthostatic hypotension, heart failure	Urinary incontinence

Adapted from Williams, B. et al. British Medical Journal (2004a) 328: 634–40.

The A/CD algorithm

The theory behind the A/CD algorithm is that patients with hypertension can broadly be classified into high- and low-renin groups. Younger patients under the age of 55 years tend to have higher renin concentrations than older patients and respond better to manipulation of the renin—angiotensin system with angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs). Older patients and those of Afro-Caribbean descent (not of mixed race, Asian or Chinese descent) have lower renin concentrations and therefore respond better to calcium channel blockers or diuretics. Table 3 summarizes these recommendations.

Table 3.

Initial pharmacological management of hypertension

	Younger (<55 years) and non-black	Older (>55 years) or of Afro-Caribbean origin
Step 1	A	C or D
Step 2	A + C or D
Step 3	A + C + D
Step 4	Add α-blocker, β-blocker or another diuretic

A, ACE inhibitor or ARB; C, calcium channel blocker; D, diuretic.

When starting antihypertensives, the emphasis should be on the need for long-term treatment, in most cases lifelong. With each stepwise change and up-titration of medication, again the patient should be involved in the management and have a clear understanding of what the goals are. Patients should be encouraged to make informed decisions about the treatment options available, including the benefits of medications and the potential side effects. They should be involved in the decision-making process to empower the individual to take responsibility for their BP, improve concordance and motivation for lifestyle measures. As a GP, you should give clear verbal and written advice about the frequency of repeat BP checks, blood tests and follow-up and emphasize the need for ongoing lifestyle modification.

Step 1

Step 1 is monotherapy with choice of either an ACE inhibitor or ARB (A) or a calcium channel blocker or diuretic (C or D) depending on the age of the patient and their ethnic group. Drugs should be started at a low dose and titrated up to the highest tolerated recommended dosage. If the response is small, then it is appropriate to switch to an alternative drug if the hypertension is mild and uncomplicated. If the hypertension is moderate or complicated, then it is appropriate to advance to Step 2. Remember that most antihypertensives take between 4 and 8 weeks to produce their maximal effect and changes should never be made on the basis of one BP reading alone.

Box 3.

Targets for BP QOF versus NICE

• Hypertension:	QOF: BP05	< 150/90	NICE	<140/90
• CKD:	QOF: CKD03	< 140/85	NICE	<140/90^*
• Diabetes:	QOF: DM12	<145/85	NICE	<140/80^**
• Stroke:	QOF: Stroke06	<150/90
• Heart disease:	QOF: CHD06	<150/90

Less than 130/80 for CKD with proteinuria.

Less than 130/80 for diabetes with evidence of end-organ damage.

Steps 2 and 3

Step 2 involves a combination of an ACE inhibitor or ARB (A) with either a calcium channel blocker or diuretic (C or D). Step 3 combines all these medications.

Step 4

Step 4 involves addition of any of an alpha-blocker, a beta-blocker or another diuretic, either a higher dose of a thiazide-type diuretic or addition of another diuretic with careful monitoring.

Beta-blockers

Beta-blockers are now not recommended as first-line therapy as they have been found to be less effective in reducing major cardiovascular events, particularly stroke, than other drug combinations. Also there is concern regarding therapy with beta-blockers and thiazide diuretics due to the increased incidence of type 2 diabetes. They can, however, be appropriate in some younger individuals who cannot tolerate ACE inhibitors or ARBs, women of childbearing age or people with evidence of increased sympathetic drive.

If a hypertensive patient is already taking a beta-blocker for no other reason than the hypertension and the BP is well controlled, there is no need to stop the beta-blocker. If the BP is not being controlled, then the dose of beta-blocker should be stepped down and stopped gradually and replaced with a more appropriate medication as per the above algorithm.

Hypertension in the elderly

Patients over the age of 80 years should be offered the same treatment as other patients over the age of 55 years, taking into account any other co-morbidity and polypharmacy. This group has been poorly represented in clinical trials but several studies show that benefits do extend to the elderly, especially reduction of cognitive impairment, strokes and cardiovascular events, although interestingly there is no change to overall mortality.

Drugs to further reduce cardiovascular risk

If the overall cardiovascular risk according to the risk calculation is over 20%, consider prescribing a statin and low-dose aspirin once the BP is under control. Aim to lower the total cholesterol to less than 4.0 mmol/l or by 25% and to a low-density lipoprotein concentration of less than 2.0 mmol/l or by 30%, whichever is the greater reduction. Although use of aspirin is widely accepted for secondary prevention, benefits in primary prevention have recently been challenged (Antithrombotic Triallists' Collaboration, 2009). However, the major recommendations and guidelines from the British Hypertension Society, Joint British Societies and NICE currently remain unchanged and suggest that aspirin should be offered after assessment of cardiovascular risk to those with 10 year CVD risk of over 20%, once BP is controlled to below 150/90 mmHg and after discussion with the patient.

Follow-up

The frequency of follow-up initially depends upon the degree of control, the number and types of therapy and patient compliance. For well-controlled hypertensives on monotherapy with no other co-morbidity, it may be reasonable to have annual review with urinalysis for proteinuria, bloods for renal function, glucose and lipids (total cholesterol plus HDLs) and a recalculation of CVD risk, if appropriate. Enquire about weight and general health and provide lifestyle advice. Discuss side effects, problems with treatment and emphasize again the importance of lifelong treatment, education and health promotion. More complicated patients with uncontrolled hypertension and co-morbidity may need to be seen much more frequently.

Key points

Hypertension is underdiagnosed and undertreated in the UK

Consider causes for secondary hypertension in young patients or those that remain uncontrolled on three antihypertensives or more

Calculate cardiovascular risk for all patients with high BP

All patients should be advised on lifestyle modifications and these changes should be emphasized at every subsequent BP assessment

Start antihypertensive medication if BP is over 160/100 mmHg or if hypertensive and CVD risk is greater than 20% or if evidence of target organ damage or diabetes

Provide clear information regarding goals of treatment, ongoing lifestyle modifications and frequency of repeat BP checks, blood tests and follow-up

References

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