Abstract 5150: The Difference in Awake Ambulatory Blood Pressure and Office Blood Pressure: A Meta-analysis
Background: Masked hypertension is associated with an increased risk of cardiovascular events, while white coat hypertension is considered to be a relatively lower risk condition; both are defined by the difference between awake ambulatory blood pressure (ABP) and office blood pressure (OBP). We review evidence on the relationship of this difference to age.
Method: We performed a systematic review of papers in PubMed using the combination of terms “office and ambulatory or home blood pressure (HBP),” and selected articles in which the OBP and awake ABP (or HBP) were presented. A random effects model was used for the meta-analyses.
Results: In the 18 studies of adults (N=8779), OBP was higher than awake ABP (the difference; 2.0±0.04/1.0±0.03 mmHg, both P<0.001); however, in the 5 studies of children and youth (N=1829), awake ABP was higher than OBP (7.9±0.12/7.9±0.10 mmHg, both P<0.001). In studies of general populations, OBP became higher than awake ABP after age 49.1/43.0 in women (N=5893) and age 44.7/44.8 in men (N=6776). In the studies comparing OBP and HBP (N=8079), OBP was higher than HBP at all ages. In the studies in which OBP, awake ABP, and HBP were all available, HBP was lower than awake ABP, and became similar to awake ABP around 65.2 years old (Figure⇓).
Conclusion: Awake ABP tends to exceed OBP at younger ages while the reverse is true after age 50; in contrast OBP tends to exceed HBP at all ages. This suggests that the prevalence of masked hypertension will be lower, while that of white coat hypertension will be greater when defined by HBP instead of ABP. The determinants of the age-related differences between ABP (or HBP) and OBP merit further investigation.