Ambulatory blood pressure monitoring in the design of antihypertensive drug trials.

The reproducibility of blood pressure estimates is considerably improved by ambulatory blood pressure monitoring compared to clinic or office readings. This reduces the number of patients required for clinical trials or improves the statistical power of the trials. Non-uniformity in the response to antihypertensive drugs makes it preferable to use crossover trials with ambulatory monitoring when comparing different antihypertensive agents. However, inherent variability of blood pressure limits the potential of these trials to determine the time-course of the action of drugs.