Problems With Blood Pressure Terminology
To the Editor:
Svetkey’s1 analysis of a notional patient presenting with seated blood pressure 132/84 serves a valuable function in summarizing the multiple nonpharmacological ways in which chronic, resting blood pressure can be reduced. At the same time, it emphasizes some anomalies and difficulties that are associated with current thinking about hypertension.
Inherent in the concept of normality is the assumption that this is a property of most members of a population. Arbitrary classification of a blood pressure of 120/80 as abnormal is therefore meaningless, given that the Gaussian distribution curves for most Western adult communities peak at values above that threshold. Consideration of blood pressures <120/80 as normal implies that reduction to this value is an ultimate end point. However, cardiovascular risk continues to fall with reductions considerably below 120/80.2,3 Together, these points suggest that normality is an impractical reference point in relation to blood pressure, and should be replaced entirely by the concept of an optimal pressure range.
Reclassification of pressures between 120/80 and 139/89 as prehypertensive was undertaken, as Svetkey1 states, to “focus increased clinical and public health attention” on the fact that this pressure range has significant associated cardiovascular risk. It is therefore potentially useful for clinicians to use the term among themselves. It is, on the other hand, potentially counterproductive to use it in communicating with a patient. Individuals who are advised that they have higher than optimal blood pressure and have the risks explained might be encouraged to undertake appropriate lifestyle changes. Individuals who are told that they have a clinical disorder are no more likely to make these lifestyle changes but are likely to demand medication in addition. Thus, adopting a practice of advising patients that they are prehypertensive can be predicted to significantly distort the community cost-effectiveness of antihypertensive treatment.4