Critical appraisal of the JNC VI, WHO/ISH and BHS guidelines for essential hypertension

Three guidelines have been selected for this review: The Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC VI), the 1999 World Health Organization-International Society of Hypertension Guidelines for the Management of Hypertension (WHO/ISH) and the Guidelines for management of hypertension: report of the third working party of the British Hypertension Society (BHS). The guidelines are generally in accordance on the principles of drug prescribing. There is, however, a serious divergence of opinion between JNC VI and BHS, and WHO/ISH on the levels of blood pressure chosen for defining hypertension and the level to which blood pressure should be reduced. In defining hypertension using ambulatory blood pressure measurement (ABPM), JNC VI and BHS recommendations for systolic blood pressure are 10-15 mmHg higher than WHO/ISH. There is even greater divergence of opinion between the guidelines on the recommended goals of treatment. Using conventional measurement WHO/ISH recommends lowering systolic blood pressure with treatment by 10-20/5-10 mmHg more than JNC VI and BHS depending on whether 'normal' or 'optimal' pressures are to be achieved. Using average daytime ABPM pressure, WHO/ISH recommends lowering the average daytime blood pressure with treatment by 10-30/5-10 mmHg more than JNC VI and BHS depending on whether 'normal' or 'optimal' blood pressures are chosen. These differing recommendations between JNC VI and BHS, and WHO/ISH cannot be reconciled and they are of such magnitude as to carry serious implications for clinical practice, not least among which is that acceptance of the WHO/ISH levels of 'normality' for blood pressure would result in some 45% of the population of all ages and nearly 60% of elderly people being classified as 'hypertensive'.