WHITE COAT EFFECT DETECTED USING SELF-MONITORING OF BLOOD-PRESSURE ATHOME - COMPARISON WITH AMBULATORY BLOOD-PRESSURE

The objective of the study was to investigate whether home blood press ure (HBP) is a reliable alternative to ambulatory blood pressure (ABP) for the detection of the white coat effect (WCE). Hypertensive patien ts were randomized to measure HBP for 2 weeks or ABP for 24 h. The alt ernative measurement was then performed. Clinic blood pressure (CBP) w as measured in the beginning and end of the study. Subjects with a dif ference of greater than or equal to 20 mm Hg systolic or greater than or equal to 10 mm Hg diastolic BP between CBP and awake ABP or CBP and HBP, were classified as clinic reactors. A total of 189 patients comp leted the study (79 on stable antihypertensive treatment). There was n o difference in the magnitude of WCE assessed using the ABP or the HBP method (mean discrepancy, systolic BP: -1.5 +/- 11.7 mm Hg, 95% CI -3 .2, 0.2; diastolic BP: 0.9 +/- 7.0, 95% CI -0.1, 1.9). A strong associ ation existed between WCE calculated using the HBP or the ABP method ( r = 0.64/0.59 systolic/diastolic, P <.001). The proportion of patients classified as clinic reactors was identical using the HBP or the ABP method (25.9%). Agreement between methods in the classification of cli nic reactors was found in 147 patients (78%). The sensitivity and spec ificity of the HBP method to classify correctly clinic reactors (ABP m ethod used as the standard) were 57% and 85%, respectively, whereas it s positive and negative predictive value were 57% and 85%. These resul ts indicate that HBP is not appropriate as an alternative to ABP diagn ostic testing in the detection of WCE. Nevertheless, HBP appears usefu l as a screening test for the detection of this phenomenon. Am J Hyper tens 1998; 11:820-827 (C) 1998 American Journal of Hypertension, Ltd.