Abandoning diastole

Whenever possible medical practice should be evidence based. Hypertension is one of the world's most common causes of premature morbidity and mortality, and national and international bodies have published guidelines on hypertension management.

Around 70% of people with known hypertension are uncontrolled

Recent guidelines have proposed that decisions on management of hypertension should take into account estimates of absolute cardiovascular risk based on an assessment of concomitant risk factors, including lipid profile, smoking habits, and the presence or absence of diabetes. While this has certain merits on scientific grounds, recommendations based on assessment of five year absolute risk ignore longer term benefits of intervention (life years saved) for younger patients who wouldbe denied treatment if shorter term estimates of risk were used.

This confusion among doctors and uncertainties about treatment strategies must be a major explanation underlying the appalling levels of blood pressure control in the United Kingdom and other European countries. The recent Health Survey for England, using the most conservative definitions of control of blood pressure (<160 mm Hg systolic and <95 mm Hg diastolic), reports that around 70% of people with known hypertension are uncontrolled and subject to high residual cardiovascular risk.

Those responsible for previous guidelines have consistently failed to communicate or facilitatethe uptake of the key messages by those who practise medicine. New guidelines in preparation, no doubt more sophisticated and comprehensive, will not address this issue. Since the old guidelines seem to have had little impact on practice, why should the new ones?

The key issue in hypertension management in primary care is the treatment of those patients whowill benefit from treatment and to ensure that treatment failures are addressed by modifying drug treatment to achieve control of blood pressure.

• Rule 1:Abandon routine diastolic blood pressure measurement. Systolic pressure is, in general, a better predictor of future cardiovascular events than diastolic pressure, which is less accurately assessed. When systolic pressure is raised, the level of diastolic pressure is usually irrelevant for the purpose of therapeutic decision making. The exception is in the case of severe hypertension where high systolic combined with high diastolic pressure—for example, >125 mm Hg—may indicate malignant hypertension, which constitutes a medical emergency.

• Rule 2:Apply the “150” systolic blood pressure rule. The “150” systolic rule is a simple, pragmatic, and more readily applicable rule than the alternative and often difficult interpretation of the various guidelines on thresholds to treat. Applied simply the threshold of 150 mm Hg systolic pressure is used as a guide for intervention following repeated measures of blood pressure over a period of weeks or months depending on the severity of the elevation.

For low risk, uncomplicated patients a more conservative approach may be adopted by raising thethreshold to 160 mm Hg. A similar threshold is widely advocated in the elderly (>60 years). In high risk patients, particularly those with diabetes, the threshold may be lowered to 140 mm Hg, in line with the recommendations of certain bodies—for example, in the sixth report of the Joint National Committee (JNC-VI) of the National High Blood Pressure Education Program.

These recommendations are broadly compatible with calculations of risk based on epidemiologicaldata and intervention trial data if “in-trial” blood pressures are used as the basis for extrapolation.

• Rule 3:Assess cardiovascular risk by examination and investigation. Cardiovascular risk assessment in people with hypertension should be based on careful examination for evidence of target organ damage (retinal vessels, cardiac enlargement or failure, or both, cerebral, or peripheral vascular pathology) and simple investigations for concomitant risk(diabetes, lipid profile) and target organ damage (electrocardiography, renal function).

• Rule 4:Modify therapy if initial drug is ineffective, partially effective, or poorly tolerated.Where treatment fails and blood pressure does not fall below the treatment threshold, drug dosage should be increased(except diuretics), treatment changed, or combinations of drugs introduced to achieve goal pressures.

Those who will no doubt challenge these proposals on the grounds of oversimplification should note that were physicians to achieve a goal systolic pressure of <150 mm Hg in the majority of their patients this would result in a reduction in their risk of a future cardiovascular event of around 25% compared with current practice and a substantial saving of deaths from heart attacks andstrokes.