Can we improve BP control rates? Lessons from the Health Survey for England 2006




Neil POULTER
MB, MSc, FRCP, FMedSci
International Centre for
Circulatory Health
Imperial College London
London, UK

by N. Poulter, United Kingdom

National and international surveys are consistent in showing that the management of hypertension is suboptimal, with a minority of hypertension patients getting their blood pressures (BPs) controlled to currently recommended targets. Raised BP is currently the biggest single contributor to global death, and the prevalence of hypertension is expected to increase over the next 2 decades. It is therefore critical to improve the management of raised BP, so that the dreadful toll on global health caused by raised BP is reduced. The reasons for the poor BP control observed around the world are multiple and various, but include inadequate use of antihypertensive agents as a result of physician inertia, drug side effects and drug costs, which adversely affect adherence to therapy, and drug resistance. Every year in England, a nationally representative survey of various aspects of health of the noninstitutionalized population takes place. Intermittently—approximately every 4 years—the focus of investigation is cardiovascular (CV) disease, which includes a systematical evaluation of BP. This database provides an invaluable source of data about mean BP levels, the prevalence of hypertension, and how BP is managed in the English adult population. In the most recent CV focus year, 2006, results showed that raised BP was being managed more effectively than in previous years (1994, 1998, and 2003), with higher rates of awareness, treatment, and control. Taking these 4 surveys into account, the key explanation for improving BP management appears to be raised levels of education among doctors and patients, which leads to raised levels of awareness, treatment, and the use of dietary measures. In addition, among those treated with drugs, more antihypertensive agents are being used to greater effect.

Medicographia. 2010;32:227-233 (see French abstract on page 233)

Raised blood pressure (BP) is currently the biggest single contributing risk factor to global death.1 Furthermore, it is estimated that the prevalence of hypertension will increase over the next two decades.2 These anticipated changes reflect two critical facts. Firstly, the world’s population is getting older, and hypertension is usually an age-related condition. Secondly, the majority of the world is in a stage of ecological transition, whereby there is increased exposure to the adverse environmental conditions that are associated with adverse cardiovascular (CV) risk, ie, “development.” These apparently “inevitable” features of “development” include increased intake of fat, calories, salt, and alcohol, increased smoking, reduced intake of fresh fruit and vegetables, and reduced physical activity. Almost all of these changes are associated with raised BP. Despite our increasing knowledge of the pathophysiology of CV diseases and the major risk factors for these disorders, such as hypertension, we face a major increase in the prevalence of hypertension, which currently generates more deaths than any other risk factor, due to the adverse effects of the process of development.

It is therefore critical that major efforts are devised for trying to prevent the currently anticipated increases in the prevalence of hypertension and that improvements in the treatment for those with hypertension are made.

It is apparent from national and international survey data from all over the world that the management of hypertension is suboptimal.3 Although there are clear variations by age, sex, and geography in the proportion of patients with hypertension who get their BPs controlled to current targets, overall a minority of patients are controlled to what is currently considered optimal. The reasons for this are multiple and vary from patient to patient, but explanations include inadequate drugs, drug side effects, poor adherence to therapy, drug costs, confusing guidelines, resistant hypertension, and physician inertia. Physicians favor all except the last of these reasons as plausible, but in reality the failure of physicians to act on currently available knowledge with currently available drugs is undoubtedly a major contributor to the suboptimal hypertension management that prevails worldwide.

This article reviews how BP treatment may be improved in terms of achieving better BP control based on evidence from the latest in the series of annual national surveys carried out in England (the Health Survey for England).

Health Survey for England: methods

The Health Survey for England (HSE) is an annual, nationally representative sample of the noninstitutionalized population of all ages randomly selected from residential addresses in England. The primary focus of the survey varies from year to year, but in 1994, 1998, 2003, and 2006, the focus was on CV disease. The detailed sampling and data collection methods have been described elsewhere.4

Data collection took place throughout the year and was essentially the same in all the CV focus years. It involved an interview, which was followed by a visit by a nurse, who measured BP, took a blood sample, and recorded the use of medicines. Sitting BP readings were taken on the right arm after 5 minutes of rest using an Omron HEM 907 and an appropriately sized cuff. BP data presented here are based on the means of the last 2 of 3 measurement. Participants were excluded if they had exercised, eaten, drunk alcohol, or smoked in the 30 minutes before BP measurement. The interviewers collected sociodemographic information, including self-assigned ethnicity, and participants were asked if they had been told by a doctor or a nurse that they had high BP. Information about diabetes mellitus and history of CV disease (angina, heart attack, or stroke) was also collected. Research ethics approval was obtained from the appropriate committees before each survey. Hypertension was defined as systolic blood pressure (SBP) ≥140 mm Hg, diastolic blood pressure (DBP) ≥90 mm Hg, or being on treatment for blood pressure. Isolated systolic hypertension was defined as follows: stage 1 was defined as an SBP of 140 to 159 mm Hg and DBP <90 mm Hg; and stage 2 was defined as SBP ≥160 mm Hg and DBP <90 mm Hg. Details of antihypertensive agents being taken, if any, were recorded by the nurse. Respondents who were not sure whether an antihypertensive drug had been prescribed to treat hypertension were considered a treated hypertensive individual if they also reported a history of hypertension. We examined the use of antihypertensive drugs by class and compared this with the current British guidelines by age and ethnicity. Analyses were restricted to participants aged ≥16 years with no missing data. Samples were weighted to allow for nonresponse differences both to the interview and then to the nurse visit. We computed awareness, treatment, and control rates among hypertensive men and women from HSE 2006 and compared these with data from previous years. Awareness was defined as a self-report of having been diagnosed as hypertensive by a doctor or nurse (excluding women during pregnancy). For control rates, we considered blood pressure target levels: <140/90 mm Hg (the target recommended in most hypertension guidelines).

Results

In 2006, 10 489 adults aged ≥16 years were interviewed and had a nurse visit. Of these, 7478 had valid blood pressure readings (3314 men and 4164 women) with a mean age of 47 years in both sexes. The full results relating to BP and hypertension of the 2006 survey have been published previously.5 Mean SBP rose across the whole age range in both men and women, but was higher in men than women until the age of 70 years (Figure 1). DBPs also rose with age in both sexes, but only until the age of 60 years, above which blood pressures fell systematically. DBPs were generally, but not always, higher in men than women. Overall mean BP levels were 130.8/ 74.2 mm Hg in men and 124.0/72.4 mm Hg in women. Hypertension rates increased with age in both sexes and were more prevalent in men than women, except in the age range 70 to 79 years.

Figure 1
Figure 1. Mean systolic (A) and diastolic (B) blood pressures by age in 2003 and 2006 for men and women.

Modified from reference 5: Falaschetti E, Chaudhury M, Mindell J, Poulter NR. Hypertension. 2009;53:480-486. Copyright © 2009, American Heart Association.

Table I
Table I. Awareness, treatment, and control among those with
hypertension (≥140/90 mm Hg or on medication) in HSE 2003
and HSE 2006.

Abbreviation: BP, blood pressure.
After reference 5: Falaschetti E, Chaudhury M, Mindell J, Poulter NR. Hypertension.
2009;53:480-486. Copyright © 2009, American Heart Association.

Overall, hypertension was observed in 30% of informants (32% of men and 29% of women), and in those aged ≥30 years, almost half of this hypertension (16% of men and 12% of women) was stage 1 isolated systolic hypertension. Mean BP levels and prevalences of hypertension in 2006 compared favorably with those reported in 2003 when mean blood pressures were 131.4/74.5mmHg inmen and 125.7/73.3mmHg in women, and overall hypertension rates were 33%and 30%, respectively.

In 2006, two thirds of those classified as hypertensive were aware of their diagnosis, awareness being more common among women than men in all age groups (Table I; and Figure 2, page 230). Among the hypertensive population, more than 60% of women, but fewer than half of the men were on treatment for hypertension. Similarly, control rates to <140/90 mm Hg were higher overall among women than men, with approximately one third and one quarter, respectively, having controlled BP levels. In 2006, of those on treatment for hypertension, 52% of informants (52%of men and 53%of women) had controlled BP (Table II, page 230). This compared with 46% (48% and 44%, respectively) for the equivalent populations in 2003. Similarly, the rates of awareness, treatment, and control observed in 2006 were all consistently greater than the equivalent figure reported in 2003, particularly among women.

Figure 2
Figure 2. Prevalence of awareness, treatment, and control of hypertension (≥140 mm Hg or on medication) in 2003 and 2006 for men (A) and women (B).

Modified from reference 5: Falaschetti E, Chaudhury M, Mindell J, Poulter NR. Hypertension. 2009;53:480-486. Copyright © 2009, American Heart Association.

Table II
Table II. Management of hypertension among those with past history
of angina, heart attack, or stroke; diabetes mellitus; and CVD
risk ≥20%.

Abbreviation: CVD, cardiovascular disease.
After reference 5: Falaschetti E, Chaudhury M, Mindell J, Poulter NR. Hypertension.
2009;53:480-486. Copyright © 2009, American Heart Association.

About three quarters of patients with a self-reported history of CV or diabetes mellitus or an estimated 10-year risk of CV disease of ≥20% were hypertensive (Table II). Of those hypertensive patients who had CV disease or diabetes mellitus, about 85% were treated and about 44% had their BPs controlled to <140/90 mm Hg. However, for those hypertensives who did not have coronary heart disease or stroke, but whose estimated CV risk was ≥20%, only 55% were treated and 17% controlled. These rates are all greater than the equivalent figures in 2003. More than 60% of patients on treatment for hypertension were receiving ≥2 antihypertensive drugs (Table III), which compares with 56% in 2003. For those receiving monotherapy, the most common agents used were blockers of the renin-angiotensin system (RAS), either angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers. Overall, diuretics, β-blockers, and calciumchannel blockers (CCBs) were the second, third, and fourth most commonly used agents, with similar levels of usage. However, this order changed when stratified by age and ethnicity (data not shown): β-blockers were clearly the second most commonly used agents for those <55 years of age, but diuretics and CCBs were more frequently used than β-blockers among older patients or those of African origin (data not shown). The most common combination of drugs among those taking 2 agents was a RAS blocker plus a diuretic, with a diuretic plus a CCB, a RAS blocker plus a β-blocker, and a RAS blocker plus a CCB having similar but lower levels of usage than a RAS blocker plus a diuretic (Table III). Again, when stratified by age and ethnicity, the order of preference changed for those aged <55 years, with greater use of RAS blockade plus β-blockers, whereas diuretics plus CCBs were used together relatively less often in this age group (data not shown). When 3 agents were used, the most common combination of agents was a RAS blocker, diuretic, and CCB, with a RAS blocker, diuretic, and β-blocker a close second. Table III
Table III. Type of drugs used in the Health Survey for England
2006.

Abbreviation: RAS, renin-angiotensin system.
After reference 5: Falaschetti E, Chaudhury M, Mindell J, Poulter NR. Hypertension.
2009;53:480-486. Copyright © 2009, American Heart Association.

Discussion

The HSE 2006 data show that for the first time in England, the majority of those treated for hypertension were controlled to the target of <140/90 mm Hg. These results represent improvements compared with HSE data from 1994, 1998, and 2003 in terms of awareness and treatment and control rates, formen and women.6-8 In the UK, the local hypertension guidelines recommend treating all BPs greater than 160/90mmHg, but for BPs >140/90 mm Hg treatment should only be initiated if the estimated 10-year CV risk is ≥20% and/or if the patient has diabetes or established CV disease.9,10 However, using 140/90 mm Hg as the recommended treatment threshold— in keeping with the latest European11 and American guidelines12—only 54% of those above this threshold were treated and, therefore overall, only 28% are controlled. Nevertheless, this compares favorably with overall control rates (using the 140/90 mm Hg definition for treatment threshold and target) in several other countries13 and with English data in earlier years.6-8 Taking the British recommendation to treat those at ≥20% 10-year risk, only 55% were treated and of those less than one third were controlled. Clearly using the more aggressive target of <130/80 mm Hg for patients with diabetes, significant renal dysfunction, or established CV disease, control rates are worse than those shown in Table II.

One of the major reasons for improved hypertension management in the UK between 1994 and 2006 is the increased use of two or more agents. In 1994, only 40% of treated patients were on ≥2 drugs for hypertension, whereas in 2006, 61% were on ≥2 drugs. The improvements reported between 1994 and 1998 were thought, in part at least, to be attributable to improved uptake of nonpharmacological advice.7 It may also be that better BP control is partly attributable to better selection of antihypertensive agents and combinations of agents, which in turnmay reflect successes of the guidelines produced by the British Hypertension Society (BHS)9,10,14 and latterly by the BHS in collaboration with the National Institute for Health and Clinical Excellence (NICE).10

These guidelines currently recommend the use of either an “A+C” (where “A” stands for ACE inhibitors or angiotensin receptor blockers and “C” for CCBs) or “A+D” (where “D” stands for diuretics) combination.

In contrast with the results in 19946 and in contradiction to the latest British Guidance, the most common first-line agent was a RAS blocker—“A” drug, using the terminology used in the British Guidelines.9,10 The most common second-line drug was a diuretic (or “D” drug), being used by 55% of patients using two agents, and the most common combination of drugs used by those using two agents was “A+D.” However, the results of the recent Avoiding Cardiovascular events through COMbination therapy in Patients LIving with Systolic Hypertension (ACCOMPLISH) trial15 show that benazepril plus amlodipine (“A+C”) was significantly superior to benazepril plus hydrochlorothiazide (“A+D”) in terms of preventing major CV events.

Furthermore, the Anglo-Scandinavian Cardiac Outcomes Trial Blood Pressure–Lowering Arm (ASCOT-BPLA) trial provided evidence of the superiority of an antihypertensive regimen using the CCB amlodipine and adding the ACE inhibitor perindopril over a regimen using a β-blocker and adding a low-dose thiazide diuretic, in terms of preventing both all-cause and CV mortality and major CV events. It may be therefore that practice changes in England to reflect the evidence base, and the combination of “A+C” may increase from its current position as the fourth most common combination used.

It is hard to tell how far the improvements in BP management that occurred between 2003 and 2006 reflect the new contract to which general practitioners have been working since April 2004,16 because improvements had been apparent between 1994 and 19987 and between 1998 and 2003.8 However, the pattern of treatment and control rates for those targets that attracted financial rewards suggests that the contract is likely to have contributed to improvements.

Meanwhile, whatever the reasons for the improvements that did occur during this 3-year period, we estimate that between 4000 and 8000 fatal or major nonfatal CV events were prevented as a result of the improved BP control apparent in Table I.

Summary and conclusions

Progressive improvement in several aspects of hypertension management—rates of awareness, treatment, and control— has been apparent in England between 1994 and 2006, as witnessed by data from four of the annual HSEs that focused on CV disease and associated risk factors. These four surveys in 1994,6 1998,7 2003,8 and 20065 provide high-quality and standardized nationally representative data on BP levels and the management of hypertension.

The determinants of the improvements observed cannot be definitely identified, but appear to include:
_ The increased use of nonpharmacological advice.
_ The increased use of more antihypertensive agents and different classes of agents.

The stimuli for these changes are again not certain, but are likely to include at least two major factors. Firstly, the publication of a series of guidelines by the BHS,9,10,14 and the attempts of this society to disseminate and implement the recommendations included in the guidelines. Secondly the new GP contract, the new General Medical Services (nGMS) contract, which included a pay-for-performance component for aspects of hypertension management, including BP control.16

During the last 15 years, the critical role that raised BP plays in terms of contributions to global death has become increasingly clear and increasing trial evidence17-19 has become available. Both types of data have helped guide and encourage improved hypertension management.

Looking to the future, “more of the same” is required—that is, continued improvements are required particularly with regard to those who are at high estimated CV risk, but who have not yet experienced CV symptoms and are not diabetic (Table II).

Meanwhile, more data are required to confirm that treating raised BP in the systolic range 140-159 mm Hg and diastolic range 90-99 mm Hg is cost-effective for subjects at low estimated CV risk. Furthermore, more data are needed to confirm which combinations of therapy are best when two, three, and four drugs are combined. Current best evidence based on two major trials ASCOT (Anglo-Scandinavian Cardiac Outcomes Trial) and ACCOMPLISH suggests “A+C” drugs are likely to be the most effective at preventing CV events,15,20 but only observational data are available to advise drug sequencing thereafter.

Whether any new drug classes—currently available (direct renin inhibitor) or in the pipeline—will impact importantly on optimal drug sequencing remains to be seen, but trials are in progress evaluating the management of resistant hypertension.

_ Neil Poulter is grateful for support from the NIHR Biomedical Research Centre funding scheme.

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