The Cardiovascular Risk of White-Coat Hypertension.

BACKGROUND: The role of white-coat hypertension (WCH) and the white-coat-effect (WCE) in development of cardiovascular disease (CVD) risk remains poorly understood. OBJECTIVES: Using data from the population-based, 11-cohort IDACO (International Database on Ambulatory Blood Pressure Monitoring in Relation to Cardiovascular Outcomes), this study compared daytime ambulatory blood pressure monitoring with conventional blood pressure measurements in 653 untreated subjects with WCH and 653 normotensive control subjects. METHODS: European Society Hypertension guidelines were used as a 5-stage risk score. Low risk was defined as 0 to 2 risk factors, and high risk was defined as ≥3 to 5 risk factors, diabetes, and/or history of prior CVD events. Age- and cohort-matching was done between 653 untreated subjects with WCH and 653 normotensive control subjects. RESULTS: In a stepwise linear regression model, systolic WCE increased by 3.8 mm Hg (95% confidence interval [CI]: 3.1 to 4.6 mm Hg) per 10-year increase in age, and was similar in low- and high-risk subjects with or without prior CVD events. Over a median 10.6-year follow-up, incidence of new CVD events was higher in 159 high-risk subjects with WCH compared with 159 cohort- and age-matched high-risk normotensive subjects (adjusted hazard ratio [HR]: 2.06; 95% CI: 1.10 to 3.84; p = 0.023). The HR was not significant for 494 participants with low-risk WCH and age-matched low-risk normotensive subjects. Subgroup analysis by age showed that an association between WCH and incident CVD events is limited to older (age ≥60 years) high-risk WCH subjects; the adjusted HR was 2.19 (95% CI: 1.09 to 4.37; p = 0.027) in the older high-risk group and 0.88 (95% CI: 0.51 to 1.53; p = 0.66) in the older low-risk group (p for interaction = 0.044). CONCLUSIONS: WCE size is related to aging, not to CVD risk. CVD risk in most persons with WCH is comparable to age- and risk-adjusted normotensive control subjects.