The importance of blood pressure control

Blood pressure
Why is it important for me to keep my blood pressure under control, when I feel well now?

Feeling well doesn't mean you are not at risk - many people are unaware of having high blood pressure (hypertension) until they have a cardiovascular event such as a heart attack or stroke.

Hypertension is one of the single biggest risk factors for coronary heart disease (CHD), which is the largest single cause of mortality in the UK (DH, 2001).

The incidence of hypertension and CHD increases with age. Over 50% of people over 65 in the UK have hypertension (Beevers et al, 1995). Hypertension is a major risk factor for having a stroke, as well as a heart attack. By reducing systolic blood pressure (BP) to 140mmHg many benefits can be seen in hypertensive patients after just six months, including:

- 24% reduction in cardiac events

- 40% reduction in stroke

- 21% reduction in all-cause mortality (Julius et al, 2004).

There has been a major change in attitude towards treating high BP in elderly people over the past 15 years, with increasing evidence that aggressive BP control in elderly people is even more rewarding in terms of reducing morbidity and mortality than treating raised BP in younger counterparts (Mulrow et al, 1994).

Side-effects
What side-effects can I expect from the medication?

Unfortunately, side-effects from antihypertensive medications are relatively common. However, if you cannot cope with the side-effects of your medication, you should come back and discuss the options with a health-care professional before you stop taking it.

Your health-care professional should be able to discuss alternative treatments that may suit you better. The five types of drugs most commonly used in the treatment of hypertension have various side-effects (see box).

Different drugs affect people in different ways and compliance drops with increasing frequency of dosage and increasing side-effects.

It may be possible to add in relatively small doses of more than one drug and reap the benefits associated with low dosages of several drugs as opposed to increasing the dose of one drug (Law et al, 2003). In this way, the side-effects may be reduced and the medication more tolerable.

Many patients need more than one class of antihypertensive in order to control BP adequately (ALLHAT, 2002). However more medications, at lower dosages, are at least as effective as, and usually have fewer side-effects than, a single drug at high dosage.

Medication decisions
What influences your decision about what to prescribe?

The British Hypertension Society (Williams et al, 2004) recommends an ABCD approach:

A - ACE inhibitor or ARB,

B - beta blocker,

C - calcium channel blocker,

D - thiazide diuretics.

Different combinations are recommended for different groups:

- Thiazide diuretics and calcium channel blockers (D and C) are recommended as the first-line therapy for all patients over 55 or who are black

- ACE inhibitors, ARBs or beta blockers (A and B) are indicated as first-line treatment for patients under 55 unless they are black

- Second-line drugs for patients on (A) or (B) should be a (C) or (D) drug, and second line for patients on (C) or (D) should be (A) or (B).

NICE recommends thiazide diuretics (D) as first-line treatment for all patients, and usually an ACE inhibitor (A) as second-line treatment. For most patients, the two guidelines are in sync for first- and second-line therapy, although the NICE guidance relies more heavily on the results of the ALLHAT study (2002), which favoured the use of thiazide diuretics.

The importance of aggressive steps to control blood pressure was highlighted by the VALUE trial (Julius et al, 1995). There are now national targets against which blood pressure treatment is monitored and adjusted. The British Hypertension Society recommends a target blood pressure of 140/85mmHg (Williams et al, 2004) while the target set by the GMS Quality and Outcomes Framework is 150/90mmHg (BMA, 2003).

Treatment options need to be evaluated according to their ability to reduce blood pressure with the least adverse side-effects. Some drugs may have added benefits that render them more suitable for some patients. For example, recent evidence from the VALUE trial (Julius et al, 2004) suggests that patients treated with the ARB, valsartan, had a 23% reduction in new-onset diabetes.

BP drugs and their possible side-effects
- Thiazide diuretics: impotence, gout, increased risk of diabetes

- Beta blockers: tiredness, shortness of breath, dizziness, cold hands and feet

- Calcium channel blockers: ankle swelling, flushing (especially of the face), palpitations

- Angiotensin-converting enzyme (ACE) inhibitors: dry cough

- Angiotensin receptor blockers (ARBs): fewer side-effects, generally very well tolerated

Author contact details
Dr Sarah C. Jarvis, Richford Gate Medical Practice, Richford Street, London W6 7HY. Email: sarah.jarvis@gp-E85016.nhs.uk

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