Higher Blood Pressure Variability in White Coat Hypertension; from the Korean Ambulatory Blood Pressure Monitoring Registry

Background and Objectives: Blood pressure variability (BPV) was recently shown to be a risk factor of stroke. White coat hypertension (WCH) used to be regarded as innocuous, but one long-term follow-up study reported that WCH increased stroke rate compared to normotension (NT). In this study, we aimed to evaluate the relationship between WCH and BPV. Subjects and Methods: We analyzed 1398 subjects from the Korean Ambulatory Blood Pressure Registry, who were divided into NT (n=364), masked hypertension (n=122), white coat hypertension (n=254), and sustained hypertension (n=658) groups. Results: Baseline characteristics were similar among groups. The average real variability (ARV), a highly sensitive BPV parameter, was highest in the WCH group, followed by the sustained hypertension, masked hypertension, and NT groups. The results persisted after being adjusted for covariates. The WCH vs. sustained hypertension results ($adjusted\;mean{\pm}standard\;error$) were as follows: 24-h systolic ARV, $22.9{\pm}0.8$ vs. $19.4{\pm}0.6$; 24-h diastolic ARV, $16.8{\pm}0.6$ vs. $14.3{\pm}0.5$; daytime systolic ARV, $21.8{\pm}0.8$ vs. $16.8{\pm}0.6$; and daytime diastolic ARV, $16.2{\pm}0.6$ vs. $13.4{\pm}0.5$ (p<0.001 for all comparisons). Conclusion: From the registry data, we found that subjects with WCH or masked hypertension had higher BPV than NT. However, long-term follow-up data assessing the clinical influences of WCH on stroke are needed.