Ambulatory 24-hour blood pressure versus self-measured blood pressure in pharmacologic trials

In recent years, indirect ambulatory 24-h blood pressure monitoring and self-measurement at home have gained increasing importance in pharmacologic studies. Both methods have important advantages over conventional casual blood pressure determinations in the clinic. The better reproducibility of blood pressure recordings by either ambulatory monitoring or home readings suggests that both techniques are superior to office readings for evaluating the effect of antihypertensive therapy. The multiple readings obtained during ambulatory 24-h monitoring or by self-measurement at home reduce the variability of blood pressure estimates and substantially decrease the number of patients needed to detect clinically relevant blood pressure differences. Furthermore, dose-response relationships of new and established antihypertensive drugs are improved, as the random effect of blood pressure measurements falls below the expected treatment effect. Although there is some overlap between the information obtained with home and ambulatory monitoring, there are also important differences. Ambulatory monitoring provides information about the diurnal profile of blood pressure and has great advantages for trials investigating the time course of a particular drug. Self-measurement can provide repeated measurements in the same situation over prolonged periods of time, and therefore is ideally suited for monitoring changes in blood pressure induced by treatment or progression of the disease. In pharmacologic studies both techniques are thus complementary.