The white coat phenomenon is benign in referred treated patients: a 14-year ambulatory blood pressure mortality study

Previous reports on the prognosis of white coat hypertension are ambiguous. We aimed to determine the prognostic implications of the white coat phenomenon in treated patients.

Our 14-year hospital-based ambulatory blood pressure (BP) monitoring prospective database was analyzed for all-cause mortality. The relationships of the white coat and masking effects with mortality were assessed both categorically (controlled awake versus clinic BP) and in a continuous mode (clinic-awake BP difference).

During the follow-up period, 2285 treated patients (aged 61 +/- 13 years, 57% women) were monitored (17621 patient-years, 286 deaths). Mean BMI was 27.8 +/- 4.5 kg/m2 and 13% were treated for diabetes. Controlled hypertension (normal clinic and awake BP) was found in 15.8%, high clinic BP (with controlled awake BP; namely, white coat uncontrolled hypertension) in 12.1%, awake hypertension (with controlled clinic BP; namely, masked uncontrolled hypertension) in 11.8%, and sustained hypertension (both clinic and awake) in 60.3%. Compared with white coat uncontrolled hypertension, age-adjusted Cox-proportional all-cause mortality hazard ratios were 1.42 (0.81-2.51) for controlled hypertension, 1.88 (1.08-3.27) for masked uncontrolled hypertension, and 2.02 (1.30-3.13) for sustained hypertension. Hazards ratios per 1% increase in the clinic-awake BP difference were 0.992 (0.983-1.002) for systolic BP and 0.981 (0.971-0.991) for diastolic BP, adjusted for age, sex, diabetes, and either systolic or diastolic awake BP, respectively.

In treated hypertensive patients referred for ambulatory BP monitoring, the white coat effect is benign compared with the reverse (masking) phenomenon, which has a poorer prognosis.