Data from the Dublin outcome study.

BACKGROUND Ambulatory blood pressure monitoring (ABPM) has proven to be a superior predictor of cardiovascular events when compared with clinic or office blood pressure measurement (CBPM). The purpose of the Dublin Outcome Study was to evaluate the predictive value of various established and new ABPM indices in a large sample of patients referred for management of cardiovascular risk. METHODS AND RESULTS At baseline 11,291 patients (5326 men, mean age 54.6 years), who were not on antihypertensive medication, underwent ABPM. Using all blood pressure readings from each individual, diastolic blood pressure was plotted against systolic blood pressure, and the regression slope was calculated. Ambulatory arterial stiffness index (AASI) was defined as one minus this regression slope. After a median follow-up of 5.3 years there were 566 cardiovascular deaths. In a Cox proportional-hazards model the unadjusted and adjusted (for other cardiovascular risk factors, mean arterial pressure and pulse pressure) hazard ratios for an abnormal AASI were 2.05 (95% confidence intervals; 1.60-2.63, P<0.0001) and 1.59 (1.23-2.04, P=0.001) respectively. CONCLUSIONS ABPM is superior to clinic or office blood pressure measurement in predicting cardiovascular mortality AASI, which may be derived simply from ABPM, is a novel index in determining prognosis.