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By Helen Williams, PGDip Cardiol, MRPharmS

Aleksey Baskakov/Dreamstime.comHypertension is remarkably common in the UK, affecting at least a quarter of the adult population, and is one of the most important preventable causes of premature morbidity and mortality. The National Institute for Health and Clinical Excellence issued updated guidance for managing hypertension last month. The clinical guideline, produced in conjunction with the British Hypertension Society, updates the recommendations published in 2006 for the diagnosis of hypertension and the initiation and monitoring of treatment.

Why is the guideline needed?

Hypertension is a major risk factor for ischaemic and haemorrhagic stroke, myocardial infarction, heart failure, chronic kidney disease, cognitive decline and premature death. Untreated hypertension is usually associated with a progressive rise in blood pressure (BP), which can cause vascular and renal damage and culminate in hypertension that is treatment-resistant.

Definitions

The guideline uses the following definitions of hypertension:

  • Stage 1 — clinic BP is =140/90mmHg and subsequent daytime average BP (measured by ambulatory BP monitoring [ABPM — see Box] or home BP monitoring [HBPM]) is =135/85mmHg
  • Stage 2 — clinic BP is =160/100mmHg and subsequent ABPM daytime average or HBPM average is =150/95mmHg
  • Severe — clinic systolic BP is =180mmHg or clinic diastolic BP is =110mmHg

Box: Ambulatory blood pressure monitoring

Ambulatory blood pressure monitoring (ABPM) involves measuring patients’ blood pressure (BP) over a 24-hour period as they go about their normal daily routine (including while they are asleep).
The patient wears a BP cuff around the upper arm, which is attached to an automated device that inflates the cuff at regular intervals during the day and night, recording the BP?each time.
ABPM provides a detailed picture of systolic and diastolic BP over the 24-hour period, with most devices calculating average daytime, night-time and 24-hour BP.

     

    Diagnostic recommendations

    A key aspect of the guideline is the diagnosis of hypertension, which, traditionally, has been based on taking several BP measurements in the clinic. However, studies have shown that ABPM correlates better with cardiovascular outcome. Moreover, recent analyses suggest that ABPM is more accurate than both clinic and HBPM in determining the presence of hypertension.

    ABPM is typically used if there is uncertainty about diagnosis, resistance to treatment, irregular BP or diurnal BP variation, or concerns about variability and “white-coat effect”.

    The new clinical guideline recommends the use of ABPM to confirm a diagnosis of hypertension, recognising that measurement of BP away from the clinic can reduce over-diagnosis and unnecessary treatment (eg, because of white-coat hypertension). In addition to improving diagnosis, this approach will save the NHS?money.

    All patients with a clinic BP of 140/90mmHg or higher, should be offered ABPM to confirm the diagnosis of hypertension. If a person is unable to tolerate ABPM, HBPM is considered a suitable alternative. People with severe hypertension should be considered for antihypertensive drug treatment immediately, without waiting for the results of ABPM or HBPM.
    The guideline recommends that, while waiting for confirmation of a diagnosis of hypertension, evidence of target organ damage (such as left-ventricular hypertrophy, chronic kidney disease and hypertensive retinopathy) should be investigated. A formal assessment of cardiovascular risk should also be undertaken, the tool for which is available in the NICE clinical guideline on lipid modification (www.nice.org.uk/cg67).

    Who should be treated?

    Antihypertensive treatment should be offered to people aged less than 80 years with stage 1 hypertension who have one or more of the following:

    • Target organ damage
    • Established cardiovascular disease
    • Renal disease
    • Diabetes
    • A 10-year cardiovascular risk equivalent to 20% or greater  

    Antihypertensive drug treatment should be offered to people of any age with stage 2 or severe hypertension.  

    Treatment targets

    The goal of antihypertensive treatment for patients under 80 years of age is a BP <140/90mmHg, since there is insufficient evidence to support lower BP targets. If ABPM or HBPM is used to monitor the response to treatment, the aim is to achieve an average daytime BP <135/85mmHg.

    The BP target for patients aged 80 years and over who require antihypertensive treatment is 150/90mmHg or less. In this age group, more aggressive treatment can be associated with poorer outcomes. If ABPM or HBPM is used to assess treatment response, the target is an average daytime BP <145/85mmHg.

    For people aged under 40 years with stage 1 hypertension (and no evidence of target organ damage, cardiovascular disease, renal disease or diabetes) clinicians should consider seeking specialist
    evaluation of secondary causes of hypertension and a more detailed assessment of potential target organ damage. This is because 10-year cardiovascular risk assessments can underestimate the lifetime risk of cardiovascular events in this younger group.

    Drug choice

    The NICE guideline recommends that, where possible, treatment should be with drugs taken once daily and that non-proprietary drugs should be prescribed if they are appropriate and minimise cost.

    Step 1

    People aged under 55 years with hypertension should be offered step 1 treatment with an angiotensin-converting enzyme inhibitor (ACEI) or a low-cost angiotensin-II receptor blocker (ARB). If an ACEI is prescribed and not tolerated, a low-cost ARB should be offered.

    People aged over 55 years, and black people of African or Caribbean family origin of any age, should be offered step 1 treatment with a calcium-channel blocker (CCB). CCBs are now favoured over thiazide-type diuretics because they demonstrate greater cost-effectiveness in most scenarios modelled (except for patients =80 years of age). In addition, the combination of an ACEI plus CCB is more effective at step 2 than ACEI plus thiazide-type diuretic. Therefore, CCBs need to be positioned strongly at step 1 to deliver optimal outcomes at step 2.

    Where a CCB is unsuitable (eg, because of intolerance, or if there is evidence or high risk of heart failure) a thiazide-like diuretic should be offered as an alternative.

    Thiazide-like diuretics, such as chlortalidone (12.5–25mg once daily) or indapamide (2.5mg once daily) should be offered in preference to conventional thiazide diuretics such as bendroflumethiazide or hydrochlorothiazide. However, the guideline states clearly that people who are already being treated with bendroflumethiazide or hydrochlorothiazide, and whose BP is stable and well controlled, should continue treatment with these drugs.     

    Step 2

    If BP is not controlled by step 1 treatment, patients should be offered combination treatment with a CCB plus an ACEI or a low-cost ARB. For black people of African or Caribbean family origin, low-cost ARBs are preferred over ACEIs, due to an increased risk of angioedema in this group. If a CCB is not suitable, a thiazide-like diuretic should be offered.

    Step 3

    If, after ensuring optimal step 2 therapy, further treatment is required, a triple combination of an ACEI (or ARB), CCB and thiazide-like diuretic should be used.

    Step 4

    For patients with resistant hypertension, further diuretic therapy should be considered.

    For patients with a serum potassium £4.5mmol/L, low-dose spironolactone (25mg once daily) is recommended — particular caution should be exercised for patients with an estimated glomerular filtration rate <60ml/min/1.73m2 due to an increased risk of hyperkalaemia.

    For people whose serum potassium is higher than 4.5mmol/L, a higher-dose thiazide-like diuretic can be considered.

    If BP remains uncontrolled despite optimal or maximal tolerated doses of four drugs, expert advice should be obtained.

    The four treatment steps are summarised in a Figure (see PDF, top right). This guidance has also been incorporated into NICE Pathways, accessible at http://pathways.nice.org.uk/pathways/hypertension.

    Helen Williams is consultant pharmacist for cardiovascular disease in south London and a member of the NICE hypertension guideline development group.

     

    Read the article on putting guidance into practice

    Citation: Clinical Pharmacist URI: 11083284

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