Guideline for the diagnosis and management of hypertension in adults — 2016

Blood pressure (BP) is an important common modifiable risk factor for cardiovascular disease. In 2014–15, 6 million adult Australians were hypertensive (BP ≥ 140/90 mmHg) or were taking BP-lowering medication.1 Hypertension is more common in those with lower household incomes and in regional areas of Australia (http://heartfoundation.org.au/about-us/what-we-do/heart-disease-in-australia/high-blood-pressure-statistics). Many Australians have untreated hypertension, including a significant proportion of Aboriginal and Torres Strait Islander people.1

Cardiovascular diseases are associated with a high level of health care expenditure.2 Controlled BP is associated with lower risks of stroke, coronary heart disease, chronic kidney disease, heart failure and death. Small reductions in BP (1–2 mmHg) are known to markedly reduce population cardiovascular morbidity and mortality.3,4

Method

The National Blood Pressure and Vascular Disease Advisory Committee, an expert committee of the National Heart Foundation of Australia, has updated the Guide to management of hypertension 2008: assessing and managing raised blood pressure in adults (last updated in 2010)5 to equip health professionals across the Australian health care system, especially those within primary care and community services, with the latest evidence to prevent, detect and manage hypertension.

International hypertension guidelines6,7,8 were reviewed to identify key areas for review. Review questions were developed using the patient problem or population, intervention, comparison and outcome(s) (PICO) framework.9 Systematic literature searches (2010–2014) of MEDLINE, Embase, CINAHL and the Cochrane Library were conducted by an external organisation, and the resulting evidence summaries informed the updated clinical recommendations. The committee also reviewed additional key literature relevant to the PICO framework up to December 2015.

Recommendations were based on high quality studies, with priority given to large systematic reviews and randomised controlled trials, and consideration of other studies where appropriate. Public consultation occurred during the development of the updated guideline. The 2016 update includes the level of evidence and strength of recommendation in accordance with National Health and Medical Research Council standards10 and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology.11 No level of evidence has been included where there was no direct evidence for a recommendation that the guideline developers agreed clearly outweighed any potential for harm.

Most of the major recommendations from the guideline are outlined below, together with background information and explanation, particularly in areas of change in practice. Key changes from the previous guideline are listed in Box 1. The full Heart Foundation Guideline for the diagnosis and management of hypertension in adults – 2016 is available at http://heartfoundation.org.au/for-professionals/clinical-information/hypertension. The full guideline contains additional recommendations in the areas of antiplatelet therapy, suspected BP variability, and initiating treatment using combination therapy compared with monotherapy.

Recommendations

Definition and classification of hypertension

Elevated BP is an established risk factor for cardiovascular disease. The relationship between BP level and cardiovascular risk is continuous, therefore the distinction between normotension and hypertension is arbitrary.12,13 Cut-off values are used for diagnosis and management decisions but vary between international guidelines. Current values for categorisation of clinic BP in Australian adults are outlined in Box 2.

Management of patients with hypertension should also consider absolute cardiovascular disease risk (where eligible for assessment) and/or evidence of end-organ damage. Several tools exist to estimate absolute cardiovascular disease risk. The National Vascular Disease Prevention Alliance developed a calculator for the Australian population, which can be found at http://www.cvdcheck.org.au.

Treatment strategies for individuals at high risk of a cardiovascular event may differ from those at low absolute cardiovascular disease risk despite similar BP readings. It is important to note that the absolute risk calculator has been developed using clinic BP, rather than ambulatory, automated office or home BP measures.

Some people are not suitable for an absolute risk assessment, including younger patients with uncomplicated hypertension and those with conditions that identify them as already at high risk.14

Blood pressure measurement

A comprehensive assessment of BP should be based on multiple measurements taken on several separate occasions. A variety of methods are available, each providing different but often complementary information. Methods include clinic BP, 24-hour ambulatory and home BP monitoring (Box 3).

Most clinical studies demonstrating effectiveness and benefits of treating hypertension have used clinic BP. Clinic, home and ambulatory BP all predict the risk of a cardiovascular event; however, home and ambulatory blood pressure measures are stronger predictors of adverse cardiovascular outcomes (Box 4).15,16

Automated office BP measurement involves taking repeated blood pressure measurements using an automated device with the clinician out of the room.17,18 This technique generally yields lower readings than conventional clinic BP and has been shown to have a good correlation with out-of-clinic measures.

The British Hypertension Society provides a list of validated BP monitoring devices.19 Use of validated and regularly maintained non-mercury devices is recommended as mercury sphygmomanometers are being phased out for occupational health and safety and environmental reasons.

Treatment thresholds

Although the benefits of lowering BP in patients with significantly elevated BP have been well established, the benefit of initiating drug therapy in patients with lower BP with or without comorbidities has been less certain. A meta-analysis of patients with uncomplicated mild hypertension (systolic BP range, 140–159 mmHg) indicated beneficial cardiovascular effects with reductions in stroke, cardiovascular death and all-cause mortality, through treatment with BP-lowering therapy.20 Corresponding relative reductions in 5-year cardiovascular disease risk were similar for all levels of baseline BP.21

Decisions to initiate drug treatment at less severe levels of BP elevations should consider a patient’s absolute cardiovascular disease risk and/or evidence of end-organ damage together with accurate blood pressure readings.

Treatment targets

Optimal blood pressure treatment targets have been debated extensively. There is emerging evidence demonstrating the benefits of treating to optimal BP, particularly among patients at high cardiovascular risk.17,20

The recent Systolic Blood Pressure Intervention Trial investigated the effect of targeting a higher systolic BP level (< 140 mmHg) compared with a lower level (< 120 mmHg) in people over the age of 50 years who were identified as having a cardiovascular 10-year risk of at least 20%.17 Many had prior cardiovascular events or mild to moderate renal impairment and most were already on BP-lowering therapy at the commencement of the study. Patients with diabetes, cardiac failure, severe renal impairment or previous stroke were excluded. The method of measurement was automated office BP,18 a technique that generally yields lower readings than conventional clinic BP. Patients treated to the lower target achieved a mean systolic BP of 121.4 mmHg and had significantly fewer cardiovascular events and lower all-cause mortality compared with the other treatment group, which achieved a mean systolic level of 136.2 mmHg. Older patients (> 75 years) benefited equally from the lower target BP. However, treatment-related adverse events increased in the more intensively treated patients, with more frequent hypotension, syncopal episodes, acute kidney injury and electrolyte abnormalities.

The selection of a BP target should be based on an informed, shared decision-making process between patient and doctor (or health care provider), considering the benefits and harms and reviewed on an ongoing basis.

Recommendations for treatment strategies and treatment targets for patients with hypertension are set out in Box 5.