Achieving better blood pressure control

Published in MedicineWise News

Date published: About this date

Clinical content may change after this date. This information is not intended as a substitute for medical advice from a qualified health professional. Health professionals should rely on their own expertise and enquiries when providing medical advice or treatment.

Key messages

  • Use a risk assessment tool to assess absolute cardiovascular risk in patients
    with uncomplicated hypertension
  • Use measurements from outside the clinic especially for patients with unusual variation between readings
  • Address lifestyle changes to reduce absolute cardiovascular risk especially smoking cessation and limiting alcohol intake
  • Start patients with uncomplicated hypertension on antihypertensive monotherapy
  • Consider coexisting conditions when choosing antihypertensive therapy

Lowering systolic blood pressure (SBP) by 10 mm Hg or diastolic blood pressure (DBP) by 5 mm Hg reduces the relative risk of cardiovascular events by about 25% and stroke by about 33%, irrespective of choice of antihypertensive.1

Treat uncomplicated hypertension according to absolute risk

Base treatment decisions on the individual’s absolute cardiovascular risk as well as blood pressure, unless the individual falls into one of the immediate treatment categories listed opposite. Blood pressure alone does not provide a complete picture of cardiovascular risk.

Assess absolute cardiovascular risk for everyone with confirmed grade 1 or 2 hypertension (SBP 140–179 mm Hg or DBP 90–109 mm Hg). Start an antihypertensive immediately, in conjunction with lifestyle changes, if the risk of a cardiovascular event in the next 5 years is high (> 15%).

Advise people at moderate (10% to 15%) or low (< 10%) risk of a cardiovascular event in the next 5 years to make or intensify lifestyle changes. Continue monitoring blood pressure and reassess absolute cardiovascular risk within 6 months (if moderate) or 12 months (if low risk).2 Start an antihypertensive if lifestyle changes have not lowered blood pressure to an acceptable level within these timeframes.

Identify those for immediate treatment

Start people on antihypertensives immediately, in conjunction with lifestyle changes, if any of the following are present:

  • grade 3 (severe) hypertension (SBP ≥ 180 mm Hg or DBP ≥ 110 mm Hg)
  • isolated systolic hypertension with widened pulse pressure
    (SBP ≥ 160 mm Hg and DBP ≤ 70 mm Hg)
  • evidence of end-organ damage
  • cardiovascular disease, hypercholesterolaemia or diabetes (if > 60 years or with microalbuminuria).

Consider immediate antihypertensive treatment for Aboriginal and Torres Strait Islander people with hypertension.2

Use risk assessment tools to estimate absolute cardiovascular risk accurately

A recent Australian study showed that GPs underestimated the absolute risk of a cardiovascular event.3 Using an absolute risk calculator such as the National Heart Foundation Australian cardiovascular risk charts can more accurately predict risk. Use the associated desktop risk calculation tool to show patients their individual risk level and to demonstrate how adhering to their medications and making lifestyle changes can reduce their risk.

Lifestyle change is essential to reduce absolute risk

Lifestyle changes can substantially improve blood pressure (Table 1), so that some people may not need to start an antihypertensive. Others may be able to delay starting or reduce the number of different drugs required to control blood pressure.2,5,6

Point out that quitting smoking markedly reduces cardiovascular risk. Encourage people to eat healthily, control their weight, reduce salt and alcohol intake and be more active. The Royal Australian College of General Practitioners SNAP Guidelines or the Australian Government Department of Health and Ageing's Lifescripts programs can be used to help people achieve and sustain lifestyle changes.

Table 1: Recommended lifestyle changes and potential impacts on blood pressureA

Modification Recommendation 
Approximate SBP reduction
Reduce weight BMI < 25 kg/m2 and waist circumference < 94 cm (males) or < 80 cm (females)
1 mm Hg per 1% reduction in weight2
Reduce salt intake < 4 g/day of salt (approximately 1600 mg sodium) 4–5 mm Hg4,7
Increase physical activity At least 30 mins physical activity most days of the week
4–9 mm Hg2,6
Modify diet Consume a diet rich in fruits, vegetables, and low fat dairy products and low in saturated and total fatB
8–14 mm Hg6
Limit alcohol intake ≤ 2 standard drinks per day8 2–4 mm Hg2,6,9,10
A. The effects of multiple interventions are not cumulative. Reductions are averages based on the results of clinical studies, and effect size varies between individuals. For comparison, individual antihypertensive medicines may reduce blood pressure by an average of 8 mm Hg.11-15
B. Normal renal function only.

Encourage reduced alcohol consumption

Encourage people to limit alcohol consumption to no more than 2 standard drinks per day.8 Reducing alcohol consumption can lower blood pressure, regardless of whether the reduction is due to the consumption of fewer drinks or through substitution with lower strength drinks.9,10

Explain measuring salt levels in processed foods

Around 75% to 80% of the salt people consume comes from processed foods.16,17 The amount of salt in different brands of the same kind of food can vary enormously.18

Advise people to choose foods that are labelled ‘low salt’ or ‘no added salt’ or compare the amount of sodium in different brands by referring to the nutrition label. Products with less than 120 mg sodium per 100 grams are low in salt.19

Identify medicines and complementary medicines that increase blood pressure

Some examples include NSAIDs, oral contraceptives, bupropion, corticosteroids, oral decongestants, venlafaxine, desvenlafaxine, duloxetine, sibutramine, reboxetine, atomoxetine, phentermine, caffeine containing herbs or drinks, St John’s wort, and liquorice.20,21 A home medicines review can identify medications that increase blood pressure.

Start with a single drug taking co-morbidities into account

Start treatment with the lowest dose of a single antihypertensive drug. Choice of drug should take into account contraindications, precautions, associated co-morbidities (Table 2), absolute cardiovascular risk and patient response. National Heart Foundation (NHF) guidelines recommend starting with an ACE inhibitor, calcium channel blocker or, in people ≥ 65 years, a low-dose thiazide diuretic.2

If the initial drug is not tolerated try an antihypertensive from a different class, again starting at the lowest dose.

Reserve angiotensin II–receptor antagonists for people who do not tolerate an ACE inhibitor. They have not been shown to be more effective than ACE inhibitors.1

Avoid starting with a fixed-dose combination

While most people will need more than one drug to control their blood pressure there is no way of determining in advance who these people will be.2,22 Initiating treatment with a combination product complicates titration of individual drugs. Additionally, it increases the risk of an adverse effect while making it difficult to identify their source.

Table 2: Coexisting conditions and antihypertensive choice (adapted from AMH20)

Coexisting condition Drugs with favourable effect Drugs with unfavourable effect
Angina Beta blockers (except oxprenolol, pindolol), calcium channel blockers
Asthma, COPD
Beta blockersC
Atrial fibrillation
ACE inhibitors or angiotensin II–receptor antagonists (verapamil, diltiazem or beta blockers may help rate control)   
Bradycardia, second- or third-degree atrioventricular block
Beta blockers, verapamil, diltiazem
Diabetes with microalbuminuria/proteinuria
ACE inhibitors, angiotensin II–receptor antagonists
Gout
Thiazide diuretics
Heart failure ACE inhibitors, beta blockers (carvedilol, controlled-release metoprolol, nebivolol, bisoprolol), thiazide diuretics, angiotensin II–receptor antagonists Calcium channel blockers (especially verapamil and diltiazem)
Post myocardial infarction Beta blockers (except oxprenolol, pindolol), ACE inhibitors, angiotensin II–receptor antagonists

C. Cardioselective beta blockers (e.g. atenolol, metoprolol) may be used cautiously in mild-to-moderate reactive airways disease.

Aim for a guideline-recommended target BP

Target2,23 clinic blood pressures are:

  • < 140/90 mm Hg for people with uncomplicated hypertension
  • < 130/80 mm Hg for people with a history of coronary heart disease, stroke, transient ischaemic attack or with diabetes, chronic kidney disease or proteinuria 300–1000 mg/dayD
  • < 125/75 mm Hg for people with proteinuria > 1000 mg/day.

Regularly discuss management with patients

When starting therapy explain to the patient

  • what their blood pressure target and their cardiovascular risk are and what they mean
  • how lifestyle changes can assist in lowering blood pressure
  • the importance of taking antihypertensives daily as high blood pressure is asymptomatic
  • the benefits and risks of treatment, and the risks of not treating
  • that they may need to take three or four different medicines to control their blood pressure.E

Almost 20% of Australian patients do not pick up their second prescription for an antihypertensive medicine.25 At subsequent visits:

  • ask how the patient is managing their medicines
  • reinforce why it is important to continue taking antihypertensives
  • address any adverse effects from drugs
  • provide information about dosage aids if patients find storing or remembering to take their medicines difficult
  • explore whether cost or other social barriers may be affecting adherence.2

Non-clinic measurement can help optimise management

Ambulatory blood pressure (ABP) monitoring or self blood-pressure monitoring may be useful in diagnosis or the investigation of:

  • white coat hypertension
  • treatment resistance
  • hypotensive symptoms, or
  • unusual variability in clinical measurements.2,5

ABP targets are lower than clinic targets.5 Normal blood pressure values when using ambulatory monitors are < 135/85 mm Hg (day time), < 120/70 mm Hg (night time), and < 130/80 mm Hg for 24 hour measures.2 Currently, there is no consensus on ambulatory thresholds for people with proteinuria or co-morbidities.F

Self-monitoring of blood pressure may encourage patients to become more active in managing their condition. It is associated with a small reduction in blood pressure (approximately 2 mm Hg) so may assist in bringing blood pressure under control.26 Make sure that the device patients receive or purchase is accurate and validated. Provide practical instruction on good technique and ensure that the device is re-calibrated every 6 months.G Mean normal blood pressure values should be < 135/85 mm Hg.2

Add a second drug from a different class if targets are not met2

Add a second drug from a different pharmacological class at a low dose, rather than increasing the dose of the first drug. If this does not control blood pressure and both drugs are tolerated, incrementally increase the dose of one drug (other than a low dose thiazide diuretic) to the maximum recommended dose before increasing the dose of the other drug.2 Trial each drug regimen for at least 6 weeks before altering doses, because a stable response takes at least 3–4 weeks.2

It is best to avoid2,20 combining:

  • verapamil with a beta-blocker due to risk of heart block
  • a potassium-sparing diuretic with an ACE inhibitor (or angiotensin II–receptor antagonist) due to the risk of hyperkalaemia
  • an ACE inhibitor with an angiotensin II–receptor antagonist as this may increase renal complications.

Consider other factors, such as secondary hypertension or sleep apnoea, if blood pressure remains high despite maximum doses of at least two appropriate agents.20,23

Use three or more antihypertensives from different classes if necessary

There is little evidence to guide combinations of three or more antihypertensives; combining drugs from different classes is preferred (e.g. ACE inhibitor, calcium-channel blocker and low-dose thiazide diuretic).2,20

Consider a fixed-dose combination product for people who are stabilised on similar doses of the individual antihypertensives

Changing to a fixed-dose combination antihypertensive, whether they contain two or three drugs, may be useful for some people taking multiple antihypertensives as they reduce pill burden, may reduce cost and may moderately improve adherence.27,28 Ensure that the available doses allow adequate titration of the component medications.22

Give clear instructions about starting a combination product

Be aware of the potential for confusion with different brand names and their different dose combinations. Ensure that patients and carers know the name and dose of all the active ingredients contained in the combination product and which medicines are being replaced by the combination product. Advise them to return unneeded medicines to their local pharmacy.

Beware the ‘triple-whammy’

Combining an ACE inhibitor or angiotensin II–receptor antagonist, a diuretic and an NSAID (including selective COX-2 inhibitors and non-prescription drugs such as ibuprofen) can cause acute renal failure. This may occur even with short-term use of the NSAID.29

There are many fixed-dose combination pills that combine a diuretic with an ACE inhibitor or an angiotensin II–receptor antagonist and it may not be clear from the brand name that the product contains two different drugs (e.g. Monoplus, Accuretic). Be aware of brands that contain a diuretic in combination with an ACE inhibitor or angiotensin II–receptor antagonist and ensure that patients and carers are aware of the dangers of using an NSAID while taking one of these products.

Only use a combined statin and antihypertensive if an individual is stabilised on both drugs

Do not use the fixed-dose combination of atorvastatin and amlodipine (Caduet) unless an individual is already stabilised on both of these drugs. Do not use this fixed-dose combination to start either amlodipine or atorvastatin, even if the individual is already taking one of these drugs, as they are more likely to discontinue. The percentage of people who have stopped taking the fixed-dose combination by 5–6 months is:

  • 19% in those who took both a calcium-channel blocker and a statin beforehand,
  • 29% in those took either a calcium-channel blocker or a statin beforehand,
  • and 43% in those who took neither a calcium-channel blocker or a statin beforehand.30

For more information see the NPS RADAR on amlodipine with atorvastatin.

D. A recent study of intensive blood-pressure control in patients with type 2 diabetes at high risk for cardiovascular events reported an increase in adverse events without any reduction in a composite outcome of fatal and nonfatal major cardiovascular events.24 However, the blood pressure target used in this study (< 120 mm Hg) was lower than current Australian guidelines. Until further evidence is available continue to aim for a SBP < 130 mm Hg in people with diabetes.
E. Patients can order free NHF brochures on managing blood pressure by calling 1300 36 27 87.
F. An updated position statement on ambulatory blood monitoring from the NHF is expected by early 2011.
G. National Heart Foundation's consumer materials on self measurement of blood pressure.
Expert reviewer

Assoc Prof Karen Duggan Director of the Hypertension Service, South Western Sydney Area Health Service Chair, National Blood Pressure & Vascular Disease Advisory Committee.

Reviewers

Dr James Best, General Practitioner, Sydney

A/Prof Nick Buckley, Consultant Clinical Pharmacologist and Toxicologist, University of New South Wales

Jan Donovan, Consumer Representative

Dr John Dowden, Editor, Australian Prescriber

Dr Graham Emblen, General Practitioner, Toowoomba

Deborah Norton, QUM Pharmacist, West Vic DGP

Susan Parker, Pharmacist, Sydney

Dr Jane Robertson, Senior Lecturer, Discipline of Clinical Pharmacology University of Newcastle

Simone Rossi, Managing Editor, Australian Medicines Handbook

Dr Guan Yeo, Clinical Education Consultant and General Practitioner, Berowra

Any correspondence regarding content should be directed to NPS. Declarations of conflicts of interest have been sought from all reviewers. The opinions expressed do not necessarily represent those of the reviewers.

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