Office blood pressure or ambulatory blood pressure for the prediction of cardiovascular events

Abstract

Aims: To determine the added value of (i) 24-h ambulatory blood pressure relative to office blood pressure and (ii) night-time ambulatory blood pressure relative to daytime ambulatory blood pressure for 10-year person-specific absolute risks of fatal and non-fatal cardiovascular events.

Methods and results: A total of 7927 participants were included from the International Database on Ambulatory blood pressure monitoring in relation to Cardiovascular Outcomes. We used cause-specific Cox regression to predict 10-year person-specific absolute risks of fatal and non-fatal cardiovascular events. Discrimination of 10-year outcomes was assessed by time-dependent area under the receiver operating characteristic curve (AUC). No differences in predicted risks were observed when comparing office blood pressure and ambulatory blood pressure. The median difference in 10-year risks (1st; 3rd quartile) was -0.01% (-0.3%; 0.1%) for cardiovascular mortality and -0.1% (-1.1%; 0.5%) for cardiovascular events. The difference in AUC (95% confidence interval) was 0.65% (0.22-1.08%) for cardiovascular mortality and 1.33% (0.83-1.84%) for cardiovascular events. Comparing daytime and night-time blood pressure, the median difference in 10-year risks was 0.002% (-0.1%; 0.1%) for cardiovascular mortality and -0.01% (-0.5%; 0.2%) for cardiovascular events. The difference in AUC was 0.10% (-0.08 to 0.29%) for cardiovascular mortality and 0.15% (-0.06 to 0.35%) for cardiovascular events.

Conclusion: Ten-year predictions obtained from ambulatory blood pressure are similar to predictions from office blood pressure. Night-time blood pressure does not improve 10-year predictions obtained from daytime measurements. For an otherwise healthy population sufficient prognostic accuracy of cardiovascular risks can be achieved with office blood pressure.

Keywords: Ambulatory blood pressure; Cardiovascular risk; Competing risks; Office blood pressure; Predictive accuracy.