P-54: Characteristics of white coat hypertension and its associated mortality risk at a tertiary hypertension center

Several prospective studies have shown that white coat (WC) hypertension is associated with a lower risk of death and/or cardiovascular morbidity and mortality than sustained hypertension. We analyzed 554 patients who had a 24 hour ambulatory blood pressure monitor (ABPM) performed at our hypertension center from 1990 to 2004, and obtained mortality information from the Social Security Death Index through 01 November 2004. WC hypertension was diagnosed when the average office systolic BPs (measured by 3 or more readings at the beginning of the monitoring period) was ≥ 10% higher than the daytime average systolic BP. The 149 patients with WC hypertension were significantly older (60.2±13.3 vs. 54.8±14.9 years, mean±standard deviation; P < 0.0001) and more likely to be female (61.1 vs. 44.2%; P < 0.0001) compared to the 405 non-WC hypertension patients. The average office BPs were significantly higher in the WC hypertensive group (156.8±18.2/88.9±10.7 mm Hg vs. 137.2±17.2/83.6±11.7 mm Hg; P < 0.0001 for both systolic and diastolic). The average 24-hour BPs were 132.7±14.8/78.7±9.2 vs. 134.6±14.8/81.6±9.9 mmHg (P = 0.16/0.002) for the WC and non-WC patients respectively. During an average of 6.8±4.1 years of possible follow-up, 16 of the 149 (10.7%) patients with WC hypertension died compared to 22 of 405 (5.4%) non-WC hypertension patients (unadjusted risk ratio=2.0, P = 0.03 by log-rank test). In a Cox proportional hazards model using 2 or 3 covariates, age was the major predictor of mortality (adjusted relative risk 1.09 per year, 95% confidence interval 1.06–1.13, P < 0.0001) and neither gender nor WC hypertension was significant (adjusted relative risk 1.15, 95% CI: 0.60–2.21 for the latter when age was the only covariate). These data suggest that, in patients undergoing 24-hour ABPM at our hypertension center, WC hypertension was associated with older age and female gender, but was not an independent predictor of mortality (after adjustment for baseline differences between the WC and other hypertensive patients).