Introduction
Globally, high blood pressure is the number one leading risk factor for mortality, and the fi fth leading risk factor for loss of DALYs (Rodgers et al.
2004). In middle- and high-income countries, such as those in Europe, high blood pressure accounts for around 17% of all deaths, and 5–6% of all DALYs lost (World Health Organization 2009).
Hypertension is a silent killer, because it is usually symptomless and can only be discovered if it is measured. Current clinical practice guidelines defi ne hypertension as a systolic blood pressure >140 mmHg and/or a diastolic blood pressure >90 mmHg (Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure 2004). Hypertension is an important risk factor for cardiovascular diseases, both ischaemic heart disease and cerebrovascular disease (or stroke). There are two main subtypes of stroke, ischaemic stroke and haemorrhagic stroke. The risk of both is elevated among those with hypertension, but the contribution of hypertension to ischaemic stroke is lower because it is more strongly affected by other risk factors.
Hypertension is very common. Estimates of the prevalence of hypertension in European countries typically range between 30 and 60% of the adult population (Wolf-Maier et al. 2003; Kearney et al. 2005). Within Europe, average blood pressure levels vary signifi cantly between countries, as shown by Figs 8.1 and 8.2. Average blood pressure levels tend to be higher in central and eastern Europe than in western Europe (Danaei et al. 2011).
Important risk factors for hypertension include high salt consumption, lack of physical exercise, obesity, smoking, excessive alcohol consumption, low intake of fruit and vegetables and psychosocial factors (Hajjar et al. 2006).
The prevalence of hypertension usually rises with age, but this age-related increase is not seen in populations with low salt consumption (INTERSALT 1988). Clearly, therefore, hypertension is amenable to primary prevention. This has partly been dealt with in Chapter 4. This chapter will focus on another
Figure 8.1 Average systolic blood pressure in men, 2008
Source: Data compiled for the Global Burden of Disease study (Mathers et al. 2008), from national and regional surveys with measured blood pressure, and adjusted using complex algorithms (Danaei et al. 2011; web appendix, web table 4)
Note: TFYR Macedonia, the former Yugoslav Republic of Macedonia
hypertension control strategy: secondary prevention by timely detection of individuals with elevated blood pressure and subsequent treatment with lifestyle advice and drugs.
Effectiveness of hypertension detection and control
Before the 1950s, hypertension was untreatable with medication. Many pages in medical textbooks were given over to its complications, including kidney and heart disease and stroke. It was not unusual, in advanced industrialized countries, to see patients with what was termed ‘malignant hypertension’, a life-threatening condition characterized by very high blood pressure and signs and symptoms of raised intracranial pressure. The situation changed markedly in the 1960s when the fi rst modern drugs for the treatment of hypertension, thiazide diuretics, were introduced. These were later followed by beta-blockers,
Figure 8.2 Average systolic blood pressure in women, 2008
Source: Data compiled for the Global Burden of Disease study (Mathers et al. 2008), from national and regional surveys with measured blood pressure, and adjusted using complex algorithms (Danaei et al. 2011; web appendix, web table 4)
Note: TFYR Macedonia, the former Yugoslav Republic of Macedonia
introduced in the 1970s, and angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers and calcium antagonists, introduced in the 1980s.
Early studies demonstrated dramatic results in reducing the complications of hypertension (Hamilton et al. 1964) and this has been confi rmed in many subsequent studies. Systematic reviews show that adequate control of hypertension by drugs reduces risks of cardiovascular diseases considerably (Blood Pressure Lowering Treatment Trialists’ Collaboration 2003; Wright and Musini 2009), also among elderly people, the main group at risk (Musini et al. 2009). For those drug treatments that have been tested against placebo, the average effect is in the order of a 30% reduction in stroke incidence, a 20% reduction in ischaemic heart disease incidence, a 20% reduction in cardiovascular death, and a 10% reduction in mortality from all causes (Blood Pressure Lowering Treatment Trialists’ Collaboration 2003).
Targets for treatment have gradually been lowered, as evidence emerged that tighter control of hypertension gives better results (Medical Research Council 1985; Blood Pressure Lowering Treatment Trialists’ Collaboration 2003);
consequently, current guidelines aim for a reduction of systolic blood pressure to
≤140 mmHg and of diastolic blood pressure to ≤ 90 mmHg (Mancia et al. 2007).
The mode of treatment has also changed. Recognizing that most people require more than one drug to achieve adequate control, low-dose combinations of drugs from different drug classes are being used increasingly in order to maximize the common blood pressure-lowering effects while minimizing the class-specifi c side-effects, thereby increasing the likelihood of adherence (Ruschitzka 2011).
Organizationally, timely detection and treatment of hypertension is a chal-lenging enterprise that requires much more than a sphygmomanometer and a prescription for drugs. A way needs to be found of reaching the large numbers of symptomless people with elevated blood pressure. In most countries, this is addressed through a proactive approach to the detection of hypertension, with measurement of blood pressure in patients consulting their doctors for other reasons. This has gradually become common practice in many high-income countries and is now included in many clinical practice guidelines. However, in addition, blood pressure measurements need to be carried out in a standardized way. Effective drugs need to be available to patients without fi nancial barriers.
Patients need to adhere to treatment and continue treatment for a long time, often lifelong. Also, regular monitoring is needed to see whether treatment goals are reached.
Realistically, this can only be done in primary care settings, but this places high demands on the system (MacMahon et al. 2008). Effective hypertension management programmes require protocols, record keeping, qualifi ed person-nel, patient education, appointment reminder systems and adequate fi nancial incentives. A recent review concluded that primary care facilities need to have an organized system of regular follow-up and review of their hypertensive patients, that drug therapy should be implemented by means of a vigorous stepped care approach when patients do not reach target blood pressure levels, and that self-monitoring and appointment reminders may be useful adjuncts to improve blood pressure control (Glynn et al. 2010).
Successes and failures of hypertension detection and control Trends in blood pressure and hypertension in Europe
Data on the detection, treatment and control of hypertension come from two complementary types of study: population-based surveys and surveys of those attending health facilities. Surveys undertaken in the population have the advantage of identifying those who may be unaware of having hypertension and of producing population-based measures of prevalence; however, while, if repeated, they can detect trends, they may be of limited value in explaining why those trends occurred. Facility-based surveys have the advantage of providing data on treatment patterns and quality of care, although they will miss those who are undiagnosed.
Figure 8.3 Reduction in average systolic blood pressure in men between 2008 and 1980
Source: Data compiled for the Global Burden of Disease study (Mathers et al. 2008), from national and regional surveys with measured blood pressure, and adjusted using complex algorithms (Danaei et al. 2011; web appendix, web table 4)
Note: TFYR Macedonia, the former Yugoslav Republic of Macedonia
Population-based surveys held over the period 1980–2005 show that average blood pressure levels have declined considerably in most western European countries, both among men and women. In most central and eastern European countries, however, trends have been less favour able, although seen over the whole period levels have declined (Figs 8.3 and 8.4) (Danaei et al. 2011). Among men in some central and eastern European countries, average blood pressure levels have risen in the most recent time period, and, as a result, total decline since 1980 has been modest (Danaei et al. 2011).
The reasons for these declines in blood pressure have been studied in only a few European countries, and the evidence for a role of improved treatment is not easy to interpret. Part of the decline is likely to be a result of reduced salt intake (see Chapter 4) and part from improved detection and treatment of
hypertension. A population-based approach to evaluation of the effectiveness of hypertension management requires distinction of ‘awareness’ (the propor-tion of all patients with hypertension reporting to have a medical diagnosis of hypertension), ‘treatment’ (the proportion of patients with hypertension reporting receiving blood pressure-lowering medications) and ‘control’ (the proportion of patients with hypertension having an average blood pressure reading <140 mmHg systolic and <90 mmHg diastolic). Unfortunately, repre-sentative national data on these parameters over time are lacking in most coun-tries and the evidence that exists is largely facility based.
It is widely believed that adherence to modern guidelines for the detection and treatment of hypertension has increased over the past decades, at least Figure 8.4 Reduction in average systolic blood pressure in women between 2008 and 1980
Source: Data compiled for the Global Burden of Disease study (Mathers et al. 2008), from national and regional surveys with measured blood pressure, and adjusted using complex algorithms (Danaei et al. 2011; web appendix, web table 4)
Note: TFYR Macedonia, the former Yugoslav Republic of Macedonia
in western Europe, although longitudinal data are very limited. A study of outpatients with cardiovascular diseases in six western European countries (United Kingdom, France, Italy, Spain and Portugal) found that, even between as late as 1998 and 2006, the proportion of patients with hypertension who had their blood pressure controlled to below the 140/90 mmHg target increased considerably, from 27 to 49% (Steinberg et al. 2008).
England is one of the countries with longitudinal data. Compliance with guidelines was probably already comparatively high in the 1990s but it increased further after 1998. For example, between 1998 and 2005, the percentage of patients whose blood pressure had been recorded rose from 87% to 99%, blood pressure control at a 150/90 mmHg level rose from 48% to 82%, and prescription of beta-blockers as maintenance therapy increased from 47% to 80% (Campbell et al. 2007).
One of the very few longitudinal population-based studies was done in Belgium. Six regional and national surveys of systolic blood pressure conducted between 1967 and 1986 were analysed, and trends in blood pressure were compared between the growing group of people receiving treatment and the group of those not receiving treatment. More than half of the decline in average systolic blood pressure could be attributed to increased treatment (Joossens and Kesteloot 1991).
In Finland, longitudinal population-based studies have also shown remark-able declines in blood pressure, not only in North Karelia, where comprehen-sive community health promotion intervention was piloted (see Chapter 4), but also in the rest of the country (Vartiainen et al. 2010). This coincided with signifi cant increases in awareness, treatment and control of hypertension.
The reductions in average blood pressure were strongest among those receiv-ing treatment for hypertension (Kastarinen et al. 2009). Although the decline in blood pressure in the population as a whole could partly be attributed to improved treatment, it was largely a result of the decline in salt consumption and an increase in physical exercise (Kastarinen et al. 2009).
These fi ndings, and others, have led researchers to conclude that at least part of the decline in uncontrolled hypertension in western Europe can be ascribed to improved management (Primatesta and Poulter 2006; Falaschetti et al. 2009).
However, all of these studies began several decades after safe and effective treatment for hypertension became available so they were beginning from a baseline at which many people were already being treated. It is important to recall that, prior to the early 1960s, no-one with hypertension was being controlled.
Despite these improvements, hypertension management is still far from optimal, as studies comparing western European countries with the United States have shown. Several facility-based studies have found consistently lower levels of control in western European countries than in the United States (Wolf-Maier et al. 2003; Wang et al. 2007) and surveys in the former USSR have demonstrated that many people who have been prescribed treatment take it only irregularly (Roberts et al. 2012).
In European facility-based surveys, the percentage of patients with known hypertension whose blood pressure is adequately controlled typically ranges between 30 and 50% (Banegas et al. 2011) (Fig. 8.5), and it is important to recall that these fi gures are almost certainly overestimates as they were obtained
from centres willing to engage in research. Consequently, the results from the Russian Federation seem inconsistent with population-level data on adherence to treatment (Roberts et al. 2010). It is clear that control has become much more widespread, although researchers often complain that blood pressure control is
‘completely inadequate’ (Kotseva et al. 2010), that resource-constrained health systems are unable to deliver care consistent with existing guidelines (Petursson et al. 2009), that many European physicians are not yet fully convinced that they should initiate treatment when blood pressure is above the threshold (Redon et al. 2011) and that more cases of stroke could be prevented if hypertension control was better (de Koning et al. 2004).
Trends in stroke incidence and mortality in Europe
One of the main aims of hypertension control is to prevent strokes. In recent years, stroke mortality has been declining in all European countries that have available data (Mirzaei et al. 2012). However, current levels of stroke mortality differ enormously between countries, and refl ect the very different historical trajectories that countries have gone through. Some countries have had consistently declining stroke mortality since the 1950s, while others fi rst saw their stroke mortality rise to a peak followed by a decline. The different moments in time at which mortality started to decline may be related to the implementation of various prevention strategies (Mirzaei et al. 2012).
Figure 8.5 Percentage of patients whose blood pressure was controlled in the EURIKA study
Source: Banegas et al. 2011
As mentioned above, there are two main subtypes of stroke. Although these have separate diagnostic codes, a defi nitive diagnosis requires brain imaging, to which access varies considerably across Europe (Leys et al. 2007). Hence, in routinely collected mortality statistics it is impossible to distinguish reliably between ischaemic and haemorrhagic stroke. Studies that have been able to make this distinction, on the basis of more detailed clinical data, suggest that mortality trends have differed considerably between the two types. In England, mortality from haemorrhagic stroke, which used to be the most frequently occurring form of the disease, has declined precipitously since the 1940s, whereas mortality from ischaemic stroke has mirrored that of ischaemic heart disease (rising until the 1970s and then declining). As a result ischaemic stroke now accounts for the majority of deaths from stroke (McCarron et al. 2006). In Austria, while mortality from both types of stroke has declined, the decline from haemorrhagic stroke has accelerated since 2000 (Bajaj et al. 2010). The more rapid decline of haemorrhagic as opposed to ischaemic stroke is compatible with the hypothesis that much of the decline in stroke results from a declining prevalence of hypertension.
Detailed research in a limited number of countries has shown that declines in stroke mortality are mainly the result of declines in incidence. In the United States, for example, stroke mortality decline began around 1960 and has been found to be largely based on declines in incidence, although improvements in survival have also made a contribution (Benatru et al. 2006; Rautio et al. 2008).
The declines in stroke incidence in the United States coincided with improved risk factor control, particularly improvements in detection and treatment of hypertension, declines in cholesterol and declines in smoking; the decline in incidence is, therefore, thought to be a result of these risk factor changes (Towfi ghi and Saver 2011).
Similar fi ndings have been reported from a few western European countries, such as Finland (Lehtonen et al. 2004; Sivenius et al. 2004) where most of the decline in stroke mortality was the result of a decline in incidence. This is consistent with the hypothesis that improved detection and treatment of hypertension has contributed to the decline in stroke mortality. In contrast, some studies in other parts of Europe, such as northern Sweden (Stegmayr and Asplund 2003) and France (Benatru et al. 2006) have attributed reductions in mortality to improved management of stroke, a fi nding also obtained in studies undertaken in the central and eastern European countries that have recorded dramatic reductions in case fatality (Korv et al. 1996; Sienkiewicz-Jarosz et al.
2011). Although a European comparative study conducted in 2004–2006 in France, Italy, Lithuania, the United Kingdom, Spain and Poland found persisting worse outcomes in Lithuania than elsewhere (Heuschmann et al. 2011), other research has shown that declines in stroke mortality in Lithuania between 1986 and 2002 were a result of improved case fatality against a background of stable incidence in men and rising incidence in women (Rastenyte et al. 2006). This suggests that improved hypertension detection and treatment has not played a role in the decline of stroke mortality in Lithuania, and not perhaps in other eastern European countries.
We now turn to trends in stroke mortality in the different parts of Europe.
As shown in Fig. 8.6, the Nordic countries, the United Kingdom and Ireland and the countries in the continental region have all seen their cerebrovascular
disease mortality decline in the last 40 years, and their mortality rates have converged to a level well below that of the EU as a whole. A study from England found that these declines were accompanied by reductions in the proportion of smokers, mean total cholesterol, mean systolic and diastolic blood pressures and major increases in premorbid treatment with antiplatelet, lipid-lowering and blood pressure-lowering drugs (Rothwell et al. 2004). Improved detection and treatment of hypertension has also contributed to the decline of ischaemic heart disease in north-west Europe. In England and Wales 10% of the decline between 1981 and 2000 was explained by declines in blood pressure (Unal et al.
2005). In Finland, similar results were found (Laatikainen et al. 2005).
Most countries in the south-west of Europe have experienced similar trends in stroke mortality as in northern and western Europe (Fig. 8.7). The main exception is Portugal, which had a much higher starting level of mortality and which, despite a substantial decline, still has a higher level of stroke mortality than the EU average. The Portuguese diet is traditionally very rich in salt, because salt was used for conservation, for example for the salted cod that is one of the pillars of Portuguese cuisine. Although the salt content of the Portuguese diet has been declining in recent decades, Portugal still has the highest rate of stroke mortality in western Europe. This is because of a high incidence, not because of high case fatality (Correia et al. 2004). The fact that a salty diet has lingered on for so much longer in Portugal may be related to the fact Portugal has long lagged behind other European countries in economic development, Figure 8.6 Trends in mortality from cerebrovascular disease in both sexes in north-western Europe, 1970–2009
Source: WHO Regional Offi ce for Europe 2012
which, in turn, refl ects Portugal’s relative isolation under the Salazar regime (Mackenbach 2009). At the same time, delays in introducing modern methods for hypertension management may also have played a role, with a study undertaken in 2003 fi nding that only 11% of those with hypertension were controlled (Macedo et al. 2005).
In contrast to other parts of Europe, mortality from stroke has fi rst risen and then fallen in many central and eastern European countries (Fig. 8.8). In this region, stroke mortality only started to decline in the 1980s (e.g. Czech Republic, Hungary) or even later (e.g. Poland, Romania). This is likely to refl ect high levels of uncontrolled hypertension (Balaz et al. 1980; Mark et al. 1991), a low priority placed on hypertension control by physicians (Mark et al. 1998) and delays in widespread prescribing of modern antihypertensive drugs.
In the USSR until 1990, access to modern antihypertensive drugs such as thiazide diuretics, beta-blockers and angiotensin-converting enzyme inhibitors was extremely limited, as was awareness among professionals and the general public of the benefi ts of regular treatment of asymptomatic individuals (Roberts et al. 2010). A survey undertaken in 2001 in eight countries of the former USSR
In the USSR until 1990, access to modern antihypertensive drugs such as thiazide diuretics, beta-blockers and angiotensin-converting enzyme inhibitors was extremely limited, as was awareness among professionals and the general public of the benefi ts of regular treatment of asymptomatic individuals (Roberts et al. 2010). A survey undertaken in 2001 in eight countries of the former USSR