PREVALENCE OF WHITE COAT EFFECT IN TREATED HYPERTENSIVE PATIENTS IN THE COMMUNITY

Patients receiving drug therapy for hypertension in the tertiary care setting frequently exhibit higher office readings compared to ambulato ry blood pressure values (white coat effect). In this study, the preva lence of a white coat effect was determined in an unselected populatio n of 147 hypertensive patients receiving treatment from their family p hysicians in the community. The proportion of patients with a white co at effect (defined as office - ambulatory blood pressure greater than or equal to 20/10 mm Hg) was significantly (P < .001) higher when base d upon the family physician's routine blood pressure readings (91/147) , compared to special readings taken by the family physician for the s tudy (54/147) or readings taken by a research nurse (30/147). There wa s a higher correlation (P < .05) between the ambulatory systolic blood pressure and the nurse's readings (r = 0.62) or special physician's r eadings (r = 0.55) v the routine physician's readings (r = 0.34). Left ventricular mass index as measured by echocardiography correlated (P < .01) with the special physician (r = 0.27), nurse (r = 0.23), and am bulatory systolic blood pressure readings (r = 0.24), but not with the routine physician's readings (r = 0.06). A white coat effect is frequ ently present in treated hypertensive patients when blood pressure is recorded by family physicians in routine clinical practice.