Home > Information for doctors >Tutorials > Hypertension Tutorial March 2000

Francisco Machado March 2000

This tutorial was prepared in March 2000. It is suggested that you also read the BHS guidelines before reading this tutorial

Contents

British guidelines on managing hypertension

BMJ 1999;319:589-590 ( 4 September )

Editorial on BHS guidelines on hypertension.

Main points

• Guidelines use North of England grading system
• Only beta blockers and diuretics have been shown to have positive effects on major outcomes e.g. heart failure, stroke and myocardial infarction
• The ALLHAT trial in the future will help us with other drug groups.
• All anti hypertensives have been shown to reduce hypertension but not all have been shown to reduce cardiovascular morbidity/mortality
• The choice of drugs with patients with co-morbidity remains controversial with different guidelines suggesting different groups of drugs for patients with different conditions
• The guidelines suggest in patients without diabetes, CVD or target organ damage but persistent BP 140-159/90-99 mmHg should be treated on the basis of their overall cardiovascular risk. They may be problems calculating this risk and what do you do with “borderline cases”. Other guidelines say treat without calculating this risk.  

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Estimation of cardiovascular risk in hypertensive patients in primary care

BJGP, 2000, 50, 127-128

  BHS guidelines suggest that patients absolute cardiovascular risk is a rational method for managing hypertension. But how good are we at estimating this risk. Study demonstrated that GPs and PNs are equally poor at estimating cardiovascular risk. Both generally underestimated risk in most cases. This has implications for the management of patients with hypertension as patients with increased risk would need treating with:

• Antihypertensive drugs to reach targets < 140/85
• Treatment of hyperlipidaemia
• Treatment with aspirin

This has cost implications
We need to use a simple cardiovascular risk tool, e.g. BHS tables  

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Pressure for change: unresolved issues in blood pressure measurement

BJGP, 1999, 49, 136-139

  Main conclusions and findings were:

• Continue using mercury sphygs for the time being until told not to. Semi automatic electronic sphys have some advantages over aneroid instruments e.g. lack of observer bias. Aneroid may become less accurate with time because of corrosion of mechanism.
• Continue to use aneroid outside the consulting room
• Consider using semi-automatic electronic devices for all untreated or uncontrolled hypertensive patients. Machines are now more reliable but have not been validated in long term trials. One suggestion is that patients who are found to have “normal” BPs with home monitors should have this confirmed with ambulatory monitoring
• Use 30-35 cm cuffs
• Screen all new and poorly controlled patients for sustained white coat hypertension
• Maintain a programme for checking all blood pressure equipment at least annually and keep staff trained

  Indications for ambulatory blood pressure monitoring

• Borderline hypertension
• Very labile hypertension
• Renal disease and diabetes if treatment is not optimal
• White coat hypertension revealed by home monitoring
• Poor BP control despite multiple therapies

There is generally a difference of  10mmHg systolic and 5mmHg diastolic between office and home BP measurements. Therefore threshold for treatment levels based on home or ABP must be adjusted down to take account of this difference. This is reflected in the BHS 1999 guidelines

Home BP monitoring: its effect on the management of hypertension in GP

BJGP, 1999, 49, 725-728.

Demonstrated that the incidence of WCHT was about 27% in newly diagnosed hypertensive patients. In the absence of any other risk factors no treatment was started in 95% of these patients with WCHT.
The study also demonstrated that patients, doctors and nurse found the instruments easy to use with few problems.
It was concluded that home monitoring could be used instead of ABP monitoring in primary care situation.
Need to develop a practice policy for home monitoring.

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Sex differences in cardiovascular disease: are women with low SEC status at high risk.

BJGP, 1999, 49, 963-966.

Dutch morbidity study of 12000 patients followed up for 10 years

Sex difference in morbidity between men and women form cardiovascular disease becomes smaller with in creasing age

Greatest morbidity in lower SEC in women compared with men. Women were also found to be less likely to be referred for further investigation, WHY?

This paper highlight the increasing morbidity of CVD disease in women esp lower SEC and the low referral rates of these women compared to their male counterparts. Also need to consider the diagnosis and management of at risk women e.g. “the hypertensive elderly lady”

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Twins and fetal programming of blood pressure

BMJ 1999;319:1313-1314 ( 20 November )

The weight of evidence linking reduced size at birth to raised blood pressure is now substantial and that for an increased risk of non-insulin dependent diabetes and coronary heart disease is increasingly convincing. Is this due to genetic or environmental effects?

Consistent with the in utero programming hypothesis, but not with the genetic alternative, both studies found a tendency for the monozygotic twin who was lightest at birth to have the highest systolic blood pressure later in life. Moreover, the larger the difference in birth weight, the larger the difference in later blood pressure

It has been suggested that we should focus on improving the nutrition of  mothers to improve birth weights. But twin studies suggest the focus should be at placental level.

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Hypertension and diabetes

Combined high blood pressure and glucose in type 2 diabetes: double jeopardy

BMJ 1998;317:693-694 ( 12 September )

UKPDS 38

Does a policy of tight blood pressure control reduce the risk of complications in diabetes? Yes, and even more convincingly so than the effect of tight blood glucose control.

Tight BP control resulted in:

• Reduction in all diabetic related endpoints including diabetic related deaths
• Reduction in diabetic microvascular disease e.g. retinopathy
• Reduction in stroke and heart failure

But not a statistical difference in all cause mortality

Also suggested that treatment should be started early

 ACEI and beta blockers were also found to be equally effective. It seems that it is the control of BP that is more important than the agent used. But there are still concerns about using calcium antagonists in diabetics.

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Survival in treated hypertension: follow up study after two decades

BMJ 1998;317:167-171 ( 18 July )

Prospective, population based observational study.

• Hypertension is a prevalent (10-20%) and important risk factor for cardiovascular disease.
• In controlled trials over 3-5 years drug treatment for hypertension prevents these complications, but little is known about long term prognosis
• During 20-22 years treated hypertensive men had a significantly increased mortality, especially from coronary heart disease, compared with non-hypertensive men from the same population
• The high incidence of myocardial infarction was related to organ damage, smoking, and cholesterol at the time of entry to the study, and to achieved serum cholesterol concentrations during follow up
• The poor prognosis for mortality from coronary heart disease is dependent upon strict monitoring of serum cholesterol concentrations

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Stopping drug treatment of hypertension: experience in 18 British general practices.
BJGP, 1999, 49, 977-80

This study looked at whether some patients antihypertensive treatment could be stopped. In 18 practices with a practice population of 34 341, 2805 (8%) pateitns aged 40-69 with hypertension were identified Of these 723 (25%) were found to be optimally controlled and to fit the criteria for the study:

·        Aged 40-69

·        Well controlled

·        No other indication for hypertensive medication

·        No major cardiovascular event

·        On treatment for more than2 years

224 patients had their anti hypertensive medication gradually withdrawn and were followed up carefully over 2 years. 22% stayed off medication. Males were more likely to stay off medication than females. Those who relapse just over half did so within three months. But lifelong observation is recommended.

Francisco Machado MM