Prognostic Information from 24-Hour Ambulatory Blood Pressure Monitoring

Some research suggests that 24-hour ambulatory blood pressure (BP) predicts cardiovascular (CV) outcomes more accurately than does clinic BP. Now, Spanish researchers provide additional insights drawn from a national primary care–based registry. The study included 64,000 adults (mean age, 58) who had guideline-specified indications for 24-hour ambulatory BP monitoring and who were followed for a mean 5 years. Patients were categorized as having sustained hypertension (elevated clinic and ambulatory readings), white-coat hypertension (elevated clinic but not ambulatory readings), masked hypertension (elevated ambulatory but not clinic readings), or normotension.

During follow-up, all-cause and CV-related mortality were 6% and 2%, respectively. Both clinic and ambulatory BP measurements (systolic and diastolic) were associated, in graded fashion, with excess all-cause and CV-related mortality. However, in models in which clinic BP was adjusted for ambulatory BP (and vice versa), ambulatory BP predicted mortality more strongly. Interestingly, masked hypertension predicted CV mortality as strongly as did sustained hypertension (whether or not patients were receiving treatment at the time of BP measurement). White-coat hypertension in untreated patients was associated with excess mortality, whereas the white-coat pattern in treated patients was not.