Conduct of therapeutic trials

Monitoring the blood pressure of individuals throughout the day and night has p;rovided information concerning the variability of blood pressure, the diurnal fluctuation of blood pressure levels, and the often exaggerated response of some individuals to the medical environment, the 'white-coat' effect. The average of multiple pressures obtained during the waking hours has been shown to correlate better with the degree of target-organ damage from hyhpertension than does the average of a few readings performed over a brief period of time in a physician's office. Thus it is generally agreed that the average ambulatory blood pressure (ABP) is more representative of the blood pressure of a subject than is the casual, clinic or office blood pressure (OBP). With the mounting evidence that lowering blood pressure in hyertensive individuals is beneficial by reducing cardiovascular complications and prolonging life, there has been a proliferation of new antihypertensive agents. Before these drugs can be released for general use, they need to be tested both for their short-term effects, peak and trough effects and duration of action, and for their long-term safety and effectiveness in reducing the number of cardiovascular events. ABP monitoring (ABPM), using the currently available portable, automatic equipment seems to be a simple, theoretically reproducible and reliable method for conducting such therapeutic trials. Yet the use of ABPM has raised a host of new questions concerning the reliability and need for standardized testing of the equipment, the definitions of hypertension and normotension, and the precise methods for quantifying the blood pressure-reducing effect of a drug and the effect of this reduction on clinical outcome. This session addressed some of these concerns.