Can ambulatory blood pressure monitoring improve the diagnosis of mild hypertension?

Hypertension is usually defined, and treatment initiated, when blood pressure exceeds a certain threshold level. This level is usually determined by a limited number of clinic measurements, which may give a poor estimate of the true level of blood pressure, because of both the inherent variability of blood pressure and the white coat effect. Another way of defining the need for treatment is the threshold decision-making approach, which describes two threshold levels, the treatment and the testing thresholds. When the pressure is between these two, further testing is indicated. Ambulatory monitoring and self-monitoring avoid the inherent limitations of clinic pressure, by increasing the number of readings and taking readings outside the clinic setting. What evidence there is indicates that ambulatory pressures do give a better measure of prognosis, and hence of the need for treatment, but better criteria are needed to define the upper normal limit. While it may be premature to recommend the widespread application of ambulatory monitoring, there are good prospects that it will provide the basis for a more rational diagnosis.