[Ambulatory blood pressure monitoring and clinical trials]

Ambulatory blood pressure monitoring (ABPM) is now widely used for the assessment of antihypertensive drugs. This procedure may be used in phase II studies in dose-ranging evaluations as well as in phase III in order to assess the drug efficacy in the patient's natural environment. The increase in the reproducibility related to the repetition of blood pressure measurements by ambulatory monitoring may improve the accuracy of the trial and minimize the numbers of subjects required. Placebo fails to lower ambulatory blood pressure in almost all studies. Nevertheless, placebo is always necessary in clinical studies with ABPM at least for the pre-inclusion phase and in order to study the peak-trough ratio. This ratio may be accurately assessed by ABPM. Finally, ABPM may be useful to rule out "white coat" responders, who are not really hypertensive patients.