Improved Hypertension Management and Control
Results From the Health Survey for England 1998
A survey in 1994 showed that among the 20% of the adult English population who were identified as hypertensive, ≈30% had their blood pressures controlled to <160 mm Hg systolic and <95 mm Hg diastolic. The 1998 Health Survey for England data update the 1994 findings in light of new thresholds and targets for treatment outlined in recent national and international guidelines. This cross-sectional survey is analyzed to describe the prevalence, awareness, treatment, and control of hypertension in a random, nationally representative sample of 11 529 English adults (≥16 years) living in noninstitutional households in 1998 and to compare these rates with those from 1994. In 1998, 20% and 37% of adults were hypertensive according to the old (systolic ≥160 mm Hg or diastolic ≥95 mm Hg) and new (systolic ≥140 mm Hg or diastolic ≥90 mm Hg) definitions, respectively. Corresponding values in 1994 were 20% and 38%. Treatment and control rates among hypertensive adults (new definition) improved from 26% to 32% and from 6% to 9%, respectively, although 60% of those on treatment received only 1 antihypertensive drug in both years. Among persons with controlled hypertension, 59% reported having received nonpharmacological advice from their physicians in 1998 compared with 30% in 1994. Rates of hypertension treatment and control have increased significantly (P=0.05 and P<0.01, respectively) since 1994 but remain low by international standards. The 1998 data suggest that improved detection, greater use of nonpharmacological measures, and increased use of >1 antihypertensive agent per patient would produce greater success in achieving target levels. This could lead to major reductions in fatal and nonfatal cardiovascular events.
The prevalence of hypertension and the levels of screening, treatment, and blood pressure control among hypertensive persons based on nationally representative data from the 1994 Health Survey for England were published.1 That report showed that according to conservative definitions, ≈20% of adults were hypertensive and that a “rule of two thirds” pertained (ie, about two thirds of hypertensive persons were aware of the problem, of whom about two thirds were receiving treatment and about two thirds of those receiving treatment had blood pressure controlled to <160/95 mm Hg). Therefore, in 1994, ≈30% of English hypertensives had their blood pressures controlled to this conservative target. This is one of the worse reported records for hypertension management in the Western world.2
In 1999, the British Hypertension Society updated their recommendations for hypertension management.3 One of the major changes between the 1999 guidelines and those previously published4 is the lowering of target blood pressure from 160/90 to 140/85 mm Hg. In addition, in the 1999 guidelines, the group eligible for intervention in the systolic blood pressure range of 140 to 159 mm Hg or diastolic blood pressure range of 90 to 99 mm Hg was defined in a more didactic manner. These more assertive threshold and target blood pressures have been reinforced by standards outlined in the National Service Framework for Coronary Heart Disease.5
In 1998, for the first time since 1994, the Health Survey for England focused on cardiovascular disease and related risk factors, including hypertension.6 Consequently, data collected in the 1998 survey provide an opportunity to compare the prevalence of hypertension and status of hypertension management with those recorded in 1994. In addition, these data provide a reasonable baseline for evaluation of the impact of recent hypertension guidelines.3,5
The Health Survey for England, an annual nationwide household survey of the English population, has been described in detail elsewhere.6 Briefly, members of a stratified random sample (drawn from the Postcode Address File) that is sociodemographically representative of the English population were invited to participate in 1998, as in 1994. The annual household response rate was ≈78% in both 1994 and 1998 but slightly lower for men and inhabitants of inner cities. Data were collected at 2 visits, with identical methods used in 1994 and 1998: an interviewer’s visit during which a questionnaire was administered, followed by a visit from a nurse, who recorded current use of prescribed medicines and whether they were prescribed for hypertension, took a blood sample, and measured blood pressure, among other investigations. Smoking habits and any history of cardiovascular events and diabetes were recorded in the questionnaire. Informants who reported a history of angina or myocardial infarction diagnosed by a physician were classified as having coronary heart disease.
Blood pressure was measured using the Dinamap 8100 monitor.7 With an appropriately sized cuff, 3 sitting blood pressure readings were taken on the right arm after 5 minutes’ rest. Informants who had eaten, drunk alcohol, or smoked in the 30 minutes before measurements were taken were excluded from analyses. Data used in this study are based on the mean of the second and third measurements.
Two definitions of hypertension are used in this report: the current use of antihypertensive medication or either (1) systolic blood pressure of ≥160 mm Hg or diastolic blood pressure of ≥95 mm Hg (old definition) or (2) systolic blood pressure of ≥140 mm Hg or diastolic blood pressure of ≥90 mm Hg (new definition). In accordance with 1994 analyses, when the respondent was not sure whether a blood pressure–lowering drug that he or she was taking had been prescribed to treat hypertension, the respondent was considered to be a treated hypertensive if he or she also reported a history of hypertension. Awareness was defined as a self-report of having been diagnosed as hypertensive by a physician or a nurse, with the exclusion of women who were diagnosed during pregnancy.
Although the most recent guidelines from the British Hypertension Society recommended a target of <140 mm Hg systolic and <85 mm Hg diastolic,3 the 2 definitions of a “controlled” hypertensive patient were a person receiving treatment who had (1) systolic blood pressure of <160 mm Hg and diastolic blood pressure of <95 mm Hg (old definition) or (2) systolic blood pressure of <140 mm Hg and diastolic blood pressure of <90 mm Hg (new definition).
The 2 definitions of isolated systolic hypertension that were used were stage Ι (systolic blood pressure of ≥140 mm Hg and diastolic blood pressure of <90 mm Hg) and stage ΙΙ (systolic blood pressure of ≥160 mm Hg and diastolic blood pressure of <90 mm Hg), which is incorporated by stage I.8 Isolated systolic hypertension rates are reported regardless of treatment for blood pressure and only among those ≥30 years old.
According to the latest British Hypertension Society guidelines, drug treatment of patients in the range of 140 to 159 mm Hg (systolic) or 90 to 99 (diastolic) should be determined by any of specified criteria, including estimated 10-year coronary heart disease risk. To estimate this risk among those surveyed, the Framingham Heart Study–based equation was applied.9 The equation has been shown to be acceptably accurate for risk prediction in northern European countries10; it includes the variables of age, gender, smoking, systolic blood pressure, total and HDL cholesterol, and diabetes and was applied to persons age ≥30 years without self-reported cardiovascular disease.
In 1998, of 15 908 adults age ≥16 years who were interviewed, 13 586 saw a survey nurse. Of these 13 586 adults, 165 were pregnant; 1285 had eaten, drunk alcohol, or smoked in the 30 minutes before blood pressure recording; and 252 had too few blood pressure readings and therefore were excluded. Of the remaining 11 884 adults who provided valid blood pressure measurements and medication details, 335 persons reported taking medication that lowered blood pressure but did not report a history of hypertension, and so they were excluded. The mean ages of the remaining 11 529 men and women included in all analyses hereafter were 46.3 (SEM 0.25) and 47.1 (0.23) years, respectively.
Mean systolic blood pressure increased with age in both genders, being higher among women than among men in those age ≥70 years. In those ≥19 years old, mean diastolic blood pressure was higher in men than in women, and diastolic blood pressure levels peaked earlier among men than among women. The overall prevalence of hypertension (old definition) was 20% in both genders (Table 1). With the new definition, the rates of hypertension were 41.5% in men and 33.3% in women (Table 1). With either definition, the prevalence of hypertension rose with age across the entire range and was higher in men than in women until the 70s.
Stage I isolated systolic hypertension was found in about one fourth of men and women age ≥30 years, with about half of men and women >70 years old being affected. Over the age of 50, the majority of cases of hypertension (new definition) were stage I isolated systolic hypertension (Table 1). Overall, stage II isolated systolic hypertension was more common in women than in men (Table 1).
Hypertension: Awareness, Treatment, and Control
More than two thirds of adults were aware of their condition, with awareness being higher among women than among men, particularly up to age 45. Almost 60% of these hypertensive persons were receiving treatment, with higher rates among women than among men, particularly up to age 45 (Table 2).
Among untreated hypertensives, 39.3% of cases were due to isolated systolic hypertension (stage II), 17.2% were due to isolated diastolic hypertension, and 43.5% were due to combined systolic and diastolic hypertension (data not shown). Among untreated hypertensives, 30.4% reported a history of high blood pressure some time in the past, 5.1% reported current high blood pressure, and 8.7% reported having treatment at some earlier stage. Overall, 38.5% of hypertensive persons had their blood pressures “controlled” (old definition), 17.4% had their blood pressures controlled according to the new definition (Table 2), and 16.4% reached the currently recommended target3 (data not shown). Control rates were higher among women than among men, particularly in those <45 years old. Of those on treatment, overall 65% had their blood pressures controlled to the more conservative target. Regardless of the definition of control that was used, the proportion of those on treatment who were controlled was lowest in the oldest age group, and proportions were similar between men and women (data not shown).
Among these hypertensive persons, almost half were aware of their condition (Table 3), with awareness being higher among women than among men, particularly in the youngest and oldest age groups. About one third of these hypertensives were receiving treatment, with higher rates among women than among men (Table 3).
Among untreated hypertensive persons, 70.6% of cases were due to isolated systolic hypertension (stage I), 3.4% were due to isolated diastolic hypertension, and 26.0% were due to combined systolic and diastolic hypertension. Among untreated hypertensives, 20.9% reported a history of high blood pressure some time in the past, 3.5% reported current high blood pressure, and 5.4% reported having treatment at some earlier stage.
Overall, 9.3% of hypertensives had their blood pressure controlled (new definition) (Table 3), and 7.4% of men and 10.3% of women had reached the British Hypertension Society target3 (data not shown). Hence, of those on treatment, 29.4% had their blood pressures controlled to <140/90 mm Hg and 28.0% had their blood pressure controlled to the British Hypertension Society target.3
Management Among Those at High Coronary Heart Disease Risk and Among Those With Cardiovascular Disease
Among the 8745 adults age ≥30 years who reported no history of coronary heart disease or stroke, 7230 had provided sufficient data to calculate a 10-year coronary heart disease risk. Among these participants, 1097 men and 326 women had a 10-year coronary heart disease risk of ≥15%. Among these 1423 persons (mean age 66.1 [0.28] years), the prevalence of hypertension according to the new definition was 74%. Of these 1053 hypertensive persons, 45% were aware, 29% were treated, and only 4% were controlled to the new definition. Among the 716 persons with coronary heart disease or stroke age ≥30 years, 41% (n=297) had their blood pressure controlled to <140/90 mm Hg (regardless of treatment), and among the 569 persons with hypertension (new definition), 72% (n=410) were treated and 26% (n=150) were controlled according to the new definition.
Comparisons Between 1994 and 1998
Mean blood pressure levels recorded in 1998 (Table 1) are similar to those reported in 1994 (men 138/76 mm Hg, women 134/73 mm Hg). Similarly in 1998, the prevalence of hypertension was 20% and 37% according to the old and new definitions, respectively, compared with corresponding values of 20% and 38% in 1994. However, awareness, treatment, and control rates were increased in 1998 compared with 1994 (Figure). With the new definition and target, control rates among those on treatment increased from 23% in 1994 to 29% in 1998.
Among the 1356 adults who received medication for hypertension in 1998, 60%, 33%, and 7% were receiving 1, 2, and ≥3 drugs, respectively. The respective values in 1994 were 60%, 34%, and 6%. The types of antihypertensive agents in use among those on monotherapy in 1998 were very similar to those in 1994; only the use of ACE inhibitors, which increased from 11% to 18%, changed significantly (Table 4). Among those receiving 2 drugs for hypertension, the most common combination changed since 1994 (Table 4).
The various definitions of hypertension and control applied to these large, nationally representative survey data allow comparisons with previous national surveys1,2 and/or reflect the most recent thresholds and recommended targets.3 These data show that the prevalence of hypertension has not decreased in England between 1994 and 1998 but that treatment and control rates have improved significantly. Much of this improvement appears to arise from increased awareness, presumably reflecting increased detection, although ≥95% of those with untreated hypertension reported that their blood pressure had been measured at some point in the past. Interestingly, control rates among those on treatment also increased between 1994 and 1998 despite the fact that among those on treatment, there was no increase in the number of antihypertensive drugs used. This suggests that either treatment thresholds have lowered or higher doses or more effective combinations of drugs were used. Although the drug combinations that were used did change (Table 4), there are no published data to suggest that these changes would produce better control. However, a possible explanation for the improved control was the finding in 1998 that of hypertensives (old definition) whose blood pressure was controlled, 59% reported receiving other advice from their general practitioner because of their condition, including advice or treatment to lose weight, to change diet, or to stop smoking, whereas in 1994, only 30% reported receiving this advice. Little objective evidence was recorded to investigate this possibility. However, mean weights of those with hypertension increased between 1994 and 1998 to the same degree as it did among the normotensive population. On the other hand, smoking rates did reduce slightly among hypertensive women, whereas smoking rates rose in normotensive women.
Using the more universally accepted new definition of hypertension, 41.5% and 33.3% of English men and women, respectively, would be considered hypertensive, and most of these cases were of isolated systolic hypertension (Table 1). Despite improvements in hypertension management shown in the 1998 survey, <1 in 10 of such hypertensive adults had their blood pressures controlled to contemporary targets.3 Even with the older, more conservative definition of hypertension for which drug treatment is not controversial, the majority (61.5%) of such hypertensive persons do not have their blood pressures controlled to old targets (<160/95 mm Hg).
Both the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure8 and the World Health Organization–International Society of Hypertension11 guidelines have lowered systolic intervention thresholds to 140 or 150 mm Hg depending on estimated risk levels, despite lack of robust trial evidence to support these recommendations. In contrast, the 1999 British Hypertension Society guidelines3 were more conservative in only recommending drug intervention in the blood pressure range of 140 to 159 mm Hg systolic or 90 to 99 mm Hg diastolic among those with diabetes, target organ damage, or an absolute 10-year coronary heart disease risk of ≥15%. It was not possible to calculate how many individuals had received blood pressure or even lipid-lowering treatment sufficient to reduce their 10-year coronary heart disease risk to <15%, and we were unable to evaluate those with target organ damage using Health Survey for England data. However, about one third of men and one twelfth of women age ≥30 years, regardless of drug treatment, had a 10-year coronary heart disease risk of ≥15%, and of these, 74% were hypertensive and only 4% had their blood pressures controlled to <140/90 mm Hg. We estimate that among those with hypertension (new definition), 55% of men and 19% of women age ≥30 years had a 10-year coronary heart disease risk of ≥15%; if target treatment levels were achieved for systolic blood pressure among these hypertensives, the proportion of those with a 10-year coronary heart disease risk of ≥15% would be reduced to 48% in men and 9% in women. In addition to the likely benefits associated with the treatment of such high-risk subjects, if systolic blood pressure were lowered by ≥10 mm Hg among the 71.5% of hypertensive subjects uncontrolled according to the old definition (Table 2), we estimate that >4000 fatal and nonfatal coronary events and >6000 fatal and nonfatal strokes could be prevented each year in England.
The use of the Dinamap 8100 for blood pressure measurement has been challenged.12 However, this machine is considered suitable and sufficiently accurate in the setting of a large multicenter survey, particularly in the blood pressure range that incorporates the targets and thresholds presented.7
The prevalence of hypertension may have been overestimated because blood pressures were measured on only 1 occasion, contrary to current recommendations.3,8,11 However, this possible overestimation will have been offset, at least in part, because blood pressure measurements were taken after 5 minutes’ rest in the home and by a nurse rather than by a physician and because the mean values of the last 2 of 3 readings were used in analyses. In addition, subjects were not included if they had eaten, drunk alcohol, or smoked within 30 minutes before blood pressure measurement. All of these factors tend to result in lower blood pressure readings than are often obtained in routine clinical practice. Based on a reproducibility study of a random sample of Health Survey for England recruits, we have previously shown that a second set of readings would lower a 20% prevalence of hypertension by ≥2.5%.1 The improved control rates observed among those with hypertension since 1994 emphasize the importance of the improved detection of hypertensive persons. The enhancement of control rates hereafter is most likely to be achieved not only through continued improvement in detection but also through an increase in the number of drugs used to lower blood pressure. Data from the HOT (Hypertension Optimal Treatment) trial13 and UKPDS (United Kingdom Prospective Diabetes Study)14 make clear that if current blood pressure targets are to be reached, the majority of patients will require ≥2 antihypertensive agents, whereas in both 1994 and 1998, among those treated, 60% were receiving 1 drug. In addition, recent trial data15–17 supply supportive evidence that the reported increase in the use of nonpharmacological advice, if acted on, will have contributed to the improved blood pressure control observed and have implications for a population-based approach to blood pressure lowering.
The National Service Framework, commissioned by the UK Department of Health,5 outlines standards of care for coronary heart disease prevention and treatment in England: general practitioners and primary care teams are required to identify persons at significant risk of cardiovascular disease and to offer them comprehensive advice and treatment to reduce their risks. The fulfillment of these requirements on a background of improvement in the management of hypertension can be expected to result in levels of blood pressure control among hypertensive persons more in keeping with those reported in the United States18 and elsewhere.2 This in turn will translate into a significant and very welcome reduction in the current high rates of cardiovascular morbidity and mortality in the United Kingdom.
The Health Survey for England is commissioned by the Department of Health. Bristol Myers-Squibb supplied an unconditional grant toward the cost of some of these analyses. The 1998 Health Survey for England was carried out by the Joint Health Survey Unit of National Center for Social Research (formerly SCPR) and Department of Epidemiology and Public Health at University College London.
- Received December 12, 2000.
- Revision received January 17, 2001.
- Accepted March 29, 2001.
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Hansson L, Zanchetti A, Carruthers SG, Dahlof B, Elmfeld D, Julius S, Menard J, Rahn KH, Wedel H, Westerling S, for the HOT Study Group. Effects of intensive blood-pressure lowering and low-dose aspirin in patients with hypertension: principal results of the Hypertension Optimal Treatment (HOT) randomised trial. Lancet. 1998; 351: 1755–1762.
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Appel LJ, Moore TJ, Obarzanek E, Vollmer WM, Svetkey LP, Sacks FM, Bray GA, Vogt TM, Cutler JA, Windhauser MM, Lin PH, Karanja N, Simons-Morton D, McCullogh M, Swain J, Steele P, Evans MA, Miller ER, Harsha DW, for the DASH Collaborative Research Group. A clinical trial of the effects of dietary patterns on blood pressure. N Engl J Med. 1997; 336: 1117–1124.
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