Education and debate

British Hypertension Society guidelines for hypertension management 1999: summary

Lawrence E Ramsay, professor of clinical pharmacology and therapeutics ^a,  Bryan Williams, professor of medicine ^b,  G Dennis Johnston, professor of clinical pharmacology ^c,  Graham A MacGregor, professor of cardiovascular medicine ^d,  Lucilla Poston, professor of fetal medicine ^e,  John F Potter, professor of medicine for the elderly ^b,  Neil R Poulter, director, cardiovascular studies unit ^f,  Gavin Russell, consultant renal physician ^g. 

^a University of Sheffield, Sheffield S10 2TN, ^b University of Leicester School of Medicine, Leicester Royal Infirmary, Leicester LE2 7LX, ^c Queen's University of Belfast, Belfast BT7 1NN, ^d Department of Medicine, St George's Hospital, London SW17 0RE, ^e Department of Obstetrics and Gynaecology, St Thomas's Hospital, London SE1 7EH, ^f Imperial College School of Medicine, London W2 1NY, ^g North Staffordshire Royal Infirmary, Stoke on Trent ST4 7LN

Correspondence to: B Williams bw17{at}leicester.ac.uk

This article summarises the new British Hypertension Society guidelines for management of hypertension, which have been published in full.¹ Since the previous guidelines ^{2 3} much new evidence has emerged on optimal blood pressure targets⁴; management of hypertension in diabetic patients^4-7; treatment of isolated systolic hypertension⁸; comparison of the antihypertensive efficacy and tolerability of different drug classes^9-11; the role of non-pharmacological measures for prevention ^{12 13} and treatment of hypertension¹⁴; and additional benefits associated with the use of aspirin and statins.

Of concern is that national surveys continue to reveal incomplete detection, treatment, and control of hypertension.¹⁵ Furthermore, treated hypertensive patients still die prematurely from cardiovascular disease.¹⁶ These guidelines aim to present the best currently available evidence on hypertension management and their implementation.

	Blood pressure measurement

All adults should have their blood pressure measured routinely at least every five years until the age of 80 years. Those with high-normal values (135-139/85-89 mm Hg) and those who have had high readings at any time previously should have their blood pressure remeasured annually. The British Hypertension Society's recommendations for measuring blood pressure should be followed (box 1).¹⁷ Seated blood pressure recordings are generally sufficient, but standing blood pressure should be measured in elderly or diabetic patients to exclude orthostatic hypotension. Ambulatory blood pressure monitoring may be helpful (box 2).

	Estimating risk of coronary heart disease or cardiovascular disease

Formal estimation of coronary heart disease risk has been proposed as an aid to treatment decisions in hypertension.¹⁸ Mindful of the strong relation between blood pressure and stroke risk, the British Hypertension Society acknowledges that targeting cardiovascular disease risk rather than coronary heart disease risk is preferable. However, to be consistent with three existing national guideline recommendations,^19-21 we recommend formal estimation of 10 year coronary heart disease risk using the Cardiac Risk Assessor computer program or the coronary heart disease risk chart issued by the Joint British Societies in their recommendations for coronary heart disease prevention.¹⁹ This pragmatic recommendation is reasonable because coronary heart disease risk is a good predictor of cardiovascular disease risk, which can be estimated by multiplying the coronary heart disease risk level by 4/3 (for example, 30% coronary heart disease risk=40% cardiovascular disease risk). Moreover, estimates of 10 year stroke risk as well as coronary heart disease risk are provided by the Joint British Societies' Cardiac Risk Assessor computer program. ^{1 19} The levels of coronary heart disease risk quoted in these guidelines will appropriately precipitate intervention for patients at higher risk of cardiovascular disease.

	Evaluation of hypertensive patients

All hypertensive patients should have a thorough history and physical examination, but need only a limited number of routine investigations (box 3). The purpose of the evaluation is to assess the cause of the hypertension, associated cardiovascular risk factors, evidence of target organ damage, and comorbid diseases, all of which may influence treatment decisions. More complex investigations may require specialist referral (box 4).

	Non-pharmacological measures

Non-pharmacological advice should be offered to all hypertensive people and those with a strong family history of hypertension. Such measures may obviate the need for drug treatment or reduce the dose or number of drugs required to control blood pressure. ^{12 14} In patients with mild hypertension but no cardiovascular complications or target organ damage, the response to these measures should be observed during the initial 4-6 month period of evaluation. When drug treatment has to be introduced more quickly, non-pharmacological measures should be instituted in parallel with drug treatment.

Good evidence from trials shows that several lifestyle modifications lower blood pressure: weight reduction to achieve an ideal body weight via reduced fat and total calorie intake¹²; regular physical exercise designed to improve fitnessthis should be predominantly dynamic (brisk walking, for example) rather than isometric (weight training); limiting alcohol consumption to <21 units per week for men and <14 units per week for women; reduced use of salt when preparing food and elimination of excessively salty foods from the diet¹⁴; increased consumption of fruit and vegetables.¹² Lifestyle modifications that further reduce cardiovascular disease risk are stopping smoking; reducing total intake of saturated fat, replacing it with polyunsaturated or monounsaturated fats; increased intake of oily fish; and regular physical exercise.

Effective implementation of these non-pharmacological measures requires enthusiasm, knowledge, patience, and time spent with patients and their families. It is best undertaken by well trained health professionalsfor example, a practice or clinic nurseand should be backed up by simple clear written information.

	Thresholds for intervention with drug treatment

Systolic blood pressure is at least as important as diastolic blood pressure as a predictor of cardiovascular disease. Systolic and diastolic blood pressure thresholds are thus provided to guide intervention with drug treatment in people with hypertension (figure).

View larger version (42K): [in this window] [in a new window]   Blood pressure thresholds and drug treatment in hypertension

	Treatment goals or "targets"

The hypertension optimal treatment (HOT) trial was underpowered but provides the best evidence to date on optimal blood pressure targets.⁴ Optimal blood pressure for reduction of major cardiovascular events (based on an analysis of patients receiving treatment) was reported to be 139/83 mm Hg and reduction of blood pressure below this level caused no harm. However, patients whose blood pressure was below 150/90 mm Hg were not apparently disadvantaged. An intention to treat analysis in hypertensive patients with diabetes showed that lowering blood pressure to below 80 mm Hg rather than below 90 mm Hg was advantageous. Recommendations for target pressures during treatment are shown in table 1. It is emphasised that even with best practice, these targets will not be achieved in all hypertensive people.

	Choice of antihypertensive drug

For each class of antihypertensive drug there are compelling indications based on sound randomised controlled trial data for use in specific patient groups, and also compelling contraindications. There are also indications and contraindications that are less clear-cut, and which are given different weight by different doctors (possible indications/contraindications). These indications and contraindications for each drug class are summarised in table 2. When none of the special considerations apply, the least expensive drug, with the most supportive trial evidencea low dose of a thiazide diureticshould be preferred.

Since publication of the previous guidelines,³ three long term, double blind studies have compared the major classes of antihypertensive drugs (thiazide,  blocker, calcium antagonist, angiotensin converting enzyme inhibitor, and  blocker) and overall showed no consistent or important differences as regards antihypertensive efficacy, side effects, or quality of life.^9-11 Differences in average response between drug classes are, however, related to age and ethnic group.¹⁰ Few trials have compared different classes of drugs directly as regards reduction in cardiovascular events,²² and none is entirely satisfactory, but they have shown no consistent differences between regimens based on different drug classes. With the exception of the systolic hypertension-Europe and systolic hypertension-China trials and the captopril prevention project study, ^{8 23 24} most evidence from outcome trials is for treatment based on thiazide or  blockers. Indirect comparison between the systolic hypertension in the elderly program,²⁵ based on diuretic treatment, and the systolic hypertension-Europe trial,⁸ based on a dihydropyridine calcium antagonist, found that the outcome with these regimens was similar.

Controlled trials of dihydropyridine calcium antagonists have not supported earlier concerns about the safety of these drugs, ^{8 23} although nifedipine in capsule form should no longer be prescribed.

	Dosage and combination therapy

The drug or formulation used should ideally be effective when taken as a single daily dose. An interval of at least four weeks to observe the full response should be allowed, unless it is necessary to lower blood pressure more urgently. The dose of drug (except thiazide diuretics) should be increased according to manufacturers' instructions. If the first drug is well tolerated but the response is small and insufficient, substitution of an alternative drug is appropriate when hypertension is mild and uncomplicated. In more severe or complicated hypertension it is safer to add drugs stepwise until blood pressure control is attained. Treatment can be stepped down later if blood pressure falls substantially below the optimal level.

Most hypertensive people will require combinations of antihypertensive therapy to achieve optimal control. ^{4 6} Drugs from different classes generally have additive effects on blood pressure when they are prescribed together. Submaximal doses of two drugs result in larger responses of blood pressure and fewer side effects than maximal doses of a single drug. Rational drug combinations combine drugs with different modes of action that are additivefor example, diuretic with  blocker, diuretic with angiotensin converting enzyme inhibitor,  blocker with calcium antagonist, calcium antagonist with angiotensin converting enzyme inhibitor. Fixed dose combinations may be convenient for patients and are acceptable when monotherapy is ineffective, individual drug components are appropriate, and there are no major cost implications.

	Elderly people with hypertension

Hypertension, including isolated systolic hypertension (160/<90 mm Hg), is found in more than half of all people aged over 60.¹⁵ These people have a higher risk of cardiovascular complications, including heart failure and dementia, than do younger people with hypertension, and antihypertensive treatment of diastolic hypertension²⁶ and isolated systolic hypertension reduces this risk. ^{8 25} Antihypertensive treatment is beneficial until at least age 80, and regular screening of blood pressure should continue until this age. Once treatment is started, it should be continued after the age of 80. When hypertension is first diagnosed in people over 80, there is limited evidence to guide policy but treatment decisions should probably be based on biological rather than chronological age. Low dose thiazides are the accepted first line treatment for elderly people.  Blockers are less effective than thiazides as first line treatment; in a meta-analysis they were shown to reduce only stroke events.²⁷ Dihydropyridine calcium antagonists are suitable alternatives for elderly patients when thiazides are ineffective, contraindicated, or not tolerated.⁸

The full version of the guidelines includes other special groups of patients: those with type I and type II diabetes; those with renal disease; pregnant women; users of oral contraceptives; users of hormone replacement therapy; and ethnic subgroups.¹

	Aspirin and hypertension

In the hypertension optimal treatment trial, 75 mg aspirin daily reduced major cardiovascular events in hypertensive patients by 15%, but not fatal events.⁴ Similar effects were observed in the hypertensive cohort within the thrombosis prevention trial of aspirin.²⁸ In both trials, however, the number of major bleeding episodes due to aspirin was similar to the number of cardiovascular events saved. Hence for primary prevention, aspirin should be considered only for hypertensive people who meet the criteria set out in box 5.    

	Treatment with statins

Several trials have shown that statin treatment reduces coronary events and all cause mortality and is safe, simple, and well tolerated in both secondary and primary prevention.¹⁹ Statin treatment also reduces stroke risk substantially in patients who have coronary heart disease.¹⁹ In subgroup analyses, benefits were similar in hypertensive patients. Given the persistent high cardiovascular risk in treated hypertensive patients, and the relation of this risk to serum cholesterol,¹⁶ these trials have large implications for hypertension management. Statin treatment could now be justified at a 10 year coronary heart disease risk of 6%,²⁹ but this would entail treating over half of all hypertensive patients. The main constraint on statin treatment at present is its cost.

The British Hypertension Society's recommendations for statin therapy are designed to be consistent with three recent sets of UK guidelines.^19-21 These are conservative recommendations and represent minimum acceptable levels of treatment. Statin treatment should be prioritised by using the criteria set out in box 5.

	Follow up

The frequency of follow up for treated patients with adequate blood pressure control depends on factors including severity and variability of blood pressure, complexity of the treatment regimen, compliance, and the need for non-pharmacological advice. Three monthly review is sufficient when treatment and blood pressure are stable; the interval should not generally exceed six months. The routine for follow up visits, at which trained nurses have an important role, should be simple: measure blood pressure and weight; inquire about general health and side effects; reinforce non-pharmacological advice; and test urine for proteinuria annually.

	Objectives of the guidelines

• To promote the primary prevention of hypertension and cardiovascular disease by encouraging changes in the diet and lifestyle of the whole population
• To increase detection and treatment of undiagnosed hypertension (particularly among those at high risk) by routine screening and increasing awareness of hypertension among the public
• To increase the proportion of patients on antihypertensive treatment who have optimal blood pressure levels
• To reduce the cardiovascular risk of treated hypertensive patients by non-pharmacological measures and by appropriate use of aspirin and statin treatment
• To promote continuation of and compliance with treatment by optimising the choice and use of drugs, minimising side effects, and increasing information and choice for patients.

	Implementation of guidelines

Realisation of these objectives will depend largely on the efforts of doctors and nurses in general practice. Surveys revealing incomplete detection, treatment, and control of hypertension indicate a serious failure to implement the knowledge we have, although there has been some improvement in recent years.¹⁵ Ideally, all practices or primary care groups should develop a protocol for hypertension management that covers screening policy; initial evaluation and investigation; estimation of cardiovascular risk; non-pharmacological measures; use of antihypertensive drugs, aspirin, and statins; treatment targets; follow up strategy; and methods for identifying and recalling patients who drop out of follow up. Written information should be available for patients about hypertension and its treatment. The protocol should detail those aspects of management that are in the province of the practice nurse and of the doctor, and the implementation of the practice policy should be audited periodically.

	Acknowledgments

The authors of this manuscript were members of the executive committee of the British Hypertension Society who formed the third working party for the production of these guidelines. LER chaired the working party and produced the first draft after receiving written sections from each member. This draft was reviewed by the membership of the British Hypertension Society and their comments were used by BW to modify subsequent drafts. BW coordinated the final writing and preparation of the manuscript which was reviewed and approved at each draft stage by all members of the working party.

	Footnotes

Competing interests: None declared.

	Appendix

Material for patients

• Patient information booklet: "Understanding High Blood Pressure"
• Fact sheets:
  Selfhelp measures
  Antihypertensive drugs
  Blood pressure measurement
  Reducing dietary salt
  Blood pressure and kidney disease
• Diet sheet: "Healthy Eating"

Material for doctors

• Blood Pressure MeasurementRecommendations of the British Hypertension Society. 3rd edition, 1997. (Edited by E O'Brien et al; price £4.95.)
• BHS/BMJ. Recommendations for Blood Pressure Measurement. CD Rom, price £58.75.

• The Joint British Societies' Cardiac Risk Assessor computer program and copies of the Joint British Societies coronary heart disease risk assessment chart can be downloaded from the British Hypertension Society website (www.hyp.ac.uk/bhs/).

	References

(Accepted 11 August 1999)