University of Minnesota

Platt-Pickering Debate the Nature of Blood Pressure

In the 1950s and after, Sir George Pickering, a towering figure in the history of blood pressure research, made the point often and emphatically: Until doctors learned to count beyond 2, they would remain incapable of understanding blood pressure as a population phenomenon.

His argument was that the clinician’s habit of dividing people into two classes, “normal” and “abnormal”, blinded them to the fundamental reality that blood pressure is a continuously distributed physiological trait. That is, in every population there occurs a distribution of blood pressure values, more frequent around the midpoint of the range and less so at the high and low extremes, with no “dividing line” to distinguish between abnormal and normal, or sick and well.

This issue prompted intense controversy early in the epidemiologic research on blood pressure, exemplified by the “Pickering-Platt debate”. Against Pickering’s view, Robert Platt argued that the highest blood pressure values in a population distinguished a discrete group who represented the disease, hypertension, and that this fact could potentially be explained by specific genetic characteristics of this group. This was no trivial point, since theory, research, and practice would all be strongly influenced by beliefs about this fundamental property of blood pressure.

Throughout the progress of epidemiologic research on blood pressure and hypertension, issues of definition and classification have persisted. The question of who is sick and who is well, with respect to blood pressure, is answered differently today than at mid-century as a result of that research. But this remains a fundamental question for policy and practice in heart attack and stroke prevention. (Darwin Labarthe)