1.1 Remit of the guideline

This guideline is designed to help practitioners tackle blood pressure problems in older patients, defined for the purposes of this guideline as over 60 years of age. While many of the principles and practices outlined in this guideline may be applied to younger patients, the guideline is targeted at the 60+ age group who are often disadvantaged in setting treatment priorities and whose risk of a serious end-point as a consequence of hypertension is much greater than for younger people.

The main aim of the guideline is to highlight the importance of treating older patients with all types of hypertension, including "mild" and isolated systolic hypertension. This area has been the cause of uncertainty among policy makers and clinicians in the past. The guideline is designed to offer practical help to those who care for patients with high blood pressure and suggests that a holistic approach to the management of cardiovascular risk should be adopted in older people. The guideline provides a system of care for older people with hypertension which will allow them to have the fullest quality of life.

While there is a strong evidence base for the treatment of hypertension in people over 60 years of age, the evidence becomes sparse for patients over 80 years. Hypertension in very old people is considered in section 6.6.

1.2 The need for a guideline on hypertension in older people

Hypertension awareness, treatment, and control rates in Scotland have increased over the past three decades, but are still poor. Age-adjusted mortality rates for stroke and coronary heart disease declined during this time period,² but not as steeply as in other countries.¹⁹ The incidence of end-stage renal disease^{3, 4} and the prevalence of heart failure and left ventricular hypertrophy are thought to be increasing.

Prevention and treatment of hypertension and target organ disease remain important public health challenges that must be addressed. A survey in England has shown that, whilst most patients with hypertension are detected, those diagnosed as hypertensive often do not continue on treatment and those treated are often not controlled satisfactorily.⁵ A recent study of US military veterans also showed that those who receive more intensive medical therapy had better blood pressure control, and that many patients did not receive sufficiently aggressive antihypertensive therapy.⁶

An important area for improving the control of blood pressure is among older people. The results in the trials of antihypertensive therapy follow a common and consistent pattern⁷ and the benefits are greater in studies which select older patients.⁸ However, there appears to be a problem in according priority to the older hypertensive patient. A study in East Anglia identified the paradox that the lowest diastolic BP at which general practitioners (GPs) would define or treat hypertension in different age groups appeared to be at variance with that recommended by the British Hypertension Society guidelines for treatment.⁹ This is illustrated in figure 1. There is also evidence that there is less awareness of, or less inclination to treat, mild hypertension and systolic hypertension in older people.^{9, 10}

Figure 1

Hypertension treatment thresholds in general practice compared with British Hypertension Society guidelines

This figure was first published in the British Medical Journal and is reproduced with permission.

The figure illustrates the mean levels of diastolic blood pressure at which GPs identified and treated hypertension for the age groups shown, as compared with the BHS guidelines for treatment current at that time.

The reasons why it was decided to accord priority to younger patients are not clear, as the benefits to older patients would be more substantial. Concerns that elderly patients might tolerate antihypertensive drugs poorly have been dispelled by analysis of adverse effects within the large outcome trials. The beneficial effects of treating hypertension greatly outweigh the incidence of adverse effects in the published trials.^{11, 12, 13, 14, 15, 16, 17}

This guideline on hypertension in older people aims to reflect national and international consensus on standards of care in hypertension and to suggest ways in which the detection and treatment of hypertension in older people in Scotland can be improved.

It is in broad agreement with the recommendations of other recently published guidelines on hypertension, such as those from the World Health Organisation and the International Society of Hypertension (WHO-ISH);¹⁸ the US Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC-VI);¹⁹ the Joint British Recommendations on prevention of coronary heart disease in clinical practice;²⁰ and the revised British Hypertension Society (BHS) guidelines.²¹

However, with the exception of the WHO guideline, none of these specifically address older people. Although other guidelines treat older patients as a subgroup, this guideline has focused on the various different pathologies that older patients suffer from and identifies therapy for subgoups of elderly patients.

This guideline has followed a systematic literature review based on a previously published Cochrane systematic review on the subject. Further details of the literature review undertaken for this guideline are provided at Annex 1.

1.3 Definition and classification: what is hypertension in older people?

The problems associated with blood pressure are those of continuously increasing risk associated with higher blood pressure. Older people are more likely than younger people to have hypertension and to benefit from treatment to bring blood pressure down. Meta-analyses of trials in hypertension in the elderly have shown that the relative risk reduction by antihypertensive treatment is about 40% for strokes and 20% for coronary events.^{12, 22, 23, 24}

The WHO-ISH guideline defines hypertension as a blood pressure (BP) >=140 mm Hg and/or a diastolic >=90 mm Hg.¹⁸ Isolated systolic hypertension (ISH) is present when the systolic BP is equal to or greater than 140 mm Hg (with a diastolic BP <90 mm Hg). ISH is particularly common among older patients.²⁵

Table 1 shows the definition and classification of different blood pressure used in this guideline.

The following important points identified in the WHO-ISH guideline¹⁸ must also be appreciated in relation to this SIGN guideline:

• Blood pressure levels are continuously related to the risks of cardiovascular disease so the definition of "hypertension" is arbitrary. Defining a level of blood pressure as hypertension does not mean that treatment is of benefit, simply that the risk is significant
• Most of the evidence about the risks and benefits of blood pressure reduction comes from trials where patients were selected on the basis of having mild to moderate hypertension.
• It is not certain whether the estimates of treatment effect obtained in trials in carefully selected hypertensive individuals can be applied to other groups, although the consistency of data from meta-analysis does suggest that treatment would be of benefit.
• High risk patients with normotension may benefit from blood pressure reduction, but further studies are required to elucidate this.

Table 1

Definitions and classifications of blood pressure levels (mm Hg)

* When a patient's systolic and diastolic blood pressure fall into different categories, the higher category should apply.

Figure 2

Cause of deaths by age in Scotland in 1997

Men

Women

1.4 Complications of hypertension

Hypertension is usually symptomless but should be treated to reduce the risk of developing complications. The prevalence and risk of developing complications of hypertension increase with age. Potential consequences of inadequate treatment of hypertension are shown in Table 2. It is worth emphasising that hypertension is the major cardiovascular risk factor that is amenable to intervention and prevention.

Table 2

Potential consequences of inadequate treatment of hypertension

Cerebrovascular disease

• Ischaemic stroke
• Haemorrhagic stroke
• Transient ischaemic attack (TIA)
• Dementia

Cardiovascular disease

• Myocardial infarction
• Angina
• Congestive cardiac failure
• Left ventricular hypertrophy
• Left ventricular dysfunction

Renal disease

Peripheral vascular disease

Aortic aneurysm

Retinopathy

Accelerated (malignant) hypertension

The main determinants of hypertension-related risk are:

• level of blood pressure
• presence of other cardiovascular risk factors
• age
• target organ damage (TOD)
• associated clinical conditions.

Multifactorial risk assessment for patients with hypertension is discussed in section 4.2.

Myocardial infarction and stroke are the leading causes of both morbidity and mortality in Scotland. These diseases become particularly common with increasing age. Figure 2 shows the increasing proportion of deaths in men and women in Scotland from cerebrovascular and ischaemic heart disease by age.²

1.5 Benefits of treating hypertension in older people

The prevalence of hypertension increases with age, as does the incidence of the diseases caused by hypertension.^{26, 27} Figure 3 shows data from the 1995 Scottish Health Survey, illustrating increasing blood pressure with age in the Scottish population. ²⁸

Figure 3

Increasing blood pressure by age in the Scottish population

There is a widespread belief that a rise in blood pressure with age is inevitable and harmless, but observational data in several populations have demonstrated that this is not so. In Western populations, mean systolic blood pressure rises steadily with increasing age: the prevalence of hypertension (>=140/90 mm Hg) or isolated systolic hypertension (>=140/<90 mm Hg) in the third US National Health and Nutrition Examination Survey (NHANES III) was more than 50% in people aged over 60 years²⁹ (although not all would be eligible for treatment). This is not seen in non-industrialised societies.³⁰

Older patients with hypertensive blood pressures have a higher risk of cardiovascular complications when compared to younger hypertensives,³¹ and treatment which reduces diastolic^{12, 13} and isolated systolic^{14, 15} hypertension reduces this risk. Recent evidence also shows a 50% reduction in heart failure in the elderly group.^{16, 17} Treatment of hypertension reduces the incidence of fatal and non-fatal stroke, cardiovascular disease (major coronary events and chronic heart failure) and, in some studies, reduces cardiovascular and total mortality.^{8, 32} The effects vary between different studies because of varying end-points (and premature halts due to impressive treatment effects), follow-up times, study population size, treatment regimen, blood pressure levels, age of participants, and presence of other risk factors.

The relative risk reduction from treatment of hypertension remains the same at all ages, but the absolute risk of complications of hypertension is higher among older patients than younger at every level of blood pressure, so that the number needed to treat (NNT) to obtain the same benefit is lower in older adults. The NNT for five years to prevent one death for patients aged under 60 years is 167 whereas for patients aged over 60 years the NNT is 72. ³³

The guideline development group acknowledges the resource implication of treating this increasingly large proportion of the population. However a study from Sweden suggests that it is cost-effective to treat hypertension in older people.³⁴ Further economic analysis in the Scottish context will be required to inform local implementation of this guideline (see Annex 2).