3.1 Evaluation

Evaluation of the patient is of value in six main areas:

• Recording the blood pressure
• Assessment of severity of hypertension
• Assessment of target organ damage
• Assessment of cardiovascular risk
• Identification of underlying causes
• Selection of specific drug therapy.

3.1.1 Recording the blood pressure

Some important points regarding blood pressure measurement are shown in Table 3 in Section 2.

3.1.2 Assessment of severity of hypertension

Accelerated phase (malignant) hypertension is now rare, but the appearance of bilateral haemorrhages and cotton wool spots on retinal examination points to the diagnosis. Without effective treatment the prognosis is poor - fewer than 10% of patients survive one year - whereas with treatment more than 80% survive five years.⁴⁴ Evidence level III

It is important to avoid sudden reduction in blood pressure in these patients, in whom autoregulation of cerebral blood flow may be temporarily impaired. This phase of hypertension is accompanied by an increased prevalence of renovascular disease.

Accelerated phase hypertension requires urgent hospital admission for investigation and treatment.

3.1.3 Assessment of target organ damage

The effect of hypertension on the end organs, i.e. brain, heart, kidneys and eyes (see Table 5) must be assessed as well as coexistent risk factors. Unilateral or segmental retinal changes are more likely to indicate branch vessel occlusion than accelerated hypertension. Clinical signs of left ventricular failure or dysfunction at presentation may also influence the urgency and mode of treatment, as may features suggesting aortic aneurysm or dissection. These are usually indications for urgent hospital admission and antihypertensive treatment.

Left ventricular failure or dysfunction at presentation requires hospital admission for investigation and treatment.

Proteinuria or haematuria in the absence of primary renal disease is a sign of severe hypertension.

3.1.4 Assessment of cardiovascular risk

This depends largely on careful elucidation of the history. Preceding cardiovascular or cerebrovascular disease immediately places the patient in a higher risk category. Such patients have a three- to five-fold increased risk of adverse outcome than a hypertensive patient without such a history.

In respect of primary prevention, most guidelines on hypertension have now adopted the concept of multiple risk assessment.^{18, 19, 20, 21, 50} These risk assessment methods base their estimates on age, gender, smoking habit, blood pressure, glucose tolerance, and cholesterol/HDL ratio. Tables, charts, computerised risk calculators are all very helpful and informative, but clinicians need to be able to recognise and identify the major risk factors (see Table 6). Details of the family history can add to the quantitative risk assessment and may reveal additional clues about underlying conditions. Body mass index (BMI) measurement should be a routine assessment at baseline and subsequently.

A full assessment of cardiovascular risk should be carried out for all hypertensive patients.

A full assessment of cardiovascular risk should be carried out for all hypertensive patients.

3.1.5 Identification of underlying causes

Identifiable and remediable causes of hypertension are found infrequently but should be actively sought where appropriate.

The most common form (probably less than 5%) of secondary hypertension in older people is renovascular disease. Clinical clues include the presence of existing vascular disease: cerebrovascular, coronary or peripheral vascular disease. Renal artery stenosis coexists in up to 30% of such patients and may influence both blood pressure control and renal function. Other causes occasionally come to light: Cushing's syndrome, phaeochromocytoma, primary aldosteronism, polycystic kidney disease. It is often possible to alter the management and, occasionally, to cure the hypertension by dealing specifically with one of these problems. However, their prevalence is low.

3.1.6 Selection of specific drug therapy

Recognition of compelling indications or contraindications for particular drugs will determine choice of therapy in many patients. For example, thiazides should be avoided in patients with gout, Beta-blockers in patients with asthma, dihydropyridines and rate limiting calcium channel antagonists in severe heart failure. By contrast, Beta-blockers may be especially useful in patients with angina, ACE inhibitors in patients with left ventricular dysfunction and dihydropyridines in patients with Raynaud's phenomenon (see section 5.2).

3.2 Investigation

Investigations should be carried out with two main objectives:

1. to aid in the assessment of cardiovascular risk; and
2. to identify patients in whom an underlying cause of hypertension may be present.

Not all tests will be required in every patient. Investigations will be tailored by how quickly blood pressure comes under control and relevant additional pathology.

3.2.1 Urinalysis

Proteinuria or haematuria can be indicators of underlying renal disease or of hypertensive nephropathy.

3.2.2 Biochemical screen

• Full blood count: an elevated mean cell volume may indicate alcohol excess.
• Serum creatinine: a normal creatinine level does not exclude renal disease. An elevated level may require further investigation. Baseline values are valuable for future reference.
• Potassium
  • Hyperkalaemia may indicate renal failure or other causes and the need for further investigations; however, haemolysis in transit is a common cause.
  • Hypokalaemia suggests aldosteronism. Hypokalaemia may be due to diuretic therapy or very rarely renovascular disease. The possibility of primary aldosteronism should be borne in mind.
• Gamma glutamyl transpeptidase (γGT): an elevation may give a clue towards alcohol abuse.
• Thyroid stimulating hormone (TSH) may be considered in the initial screen of the hypertensive patient because it will identify a readily treatable condition and may explain some cases of dyslipidaemia. Hypothyroidism may be associated with hypertension in certain patients.
• Blood glucose and full lipid profile (total and HDL cholesterol and triglycerides) help define cardiovascular risk more accurately. The value of lipid measurements in patients over 75 years is not fully established. Although screening tests need not necessarily be fasting, treatment decisions should be based on a fasting sample.
• Serum urate may be useful as a baseline before initiating diuretic therapy
• Serum calcium profile should be measured to exclude hyperparathyroidism, which is associated with hypertension in some patients.

3.2.3 Cardiac assessment

All hypertensive patients should have a standard 12 lead ECG. This provides a baseline for future reference and will reveal evidence of myocardial ischaemia, conduction defects and left ventricular hypertrophy.

Echocardiography is increasingly available. It is more sensitive than the ECG and is particularly helpful in further assessment of a cardiac murmur, in identifying left ventricular dysfunction requiring treatment, and in defining left ventricular hypertrophy. However, there are significant difficulties with standardisation of the technique and the intra- and inter-observer variability remains a problem. The availability of echocardiography will depend on local facilities and expertise.

3.2.4 Additional investigations

Further investigation of brain, heart, kidneys and endocrine system may be appropriate in selected individuals. Additional diagnostic tests will usually require specialist referral. These are often undertaken in ascending order of invasiveness and complexity.