WHITE-COAT HYPERTENSION - A SELECTION BIAS

Background Results of several studies have shown that subjects with wh ite-coat hypertension (WCH) have more target-organ damage than do norm otensive controls with similar ambulatory blood pressures. Objective T o investigate whether this is due to a selection bias. Setting Sevente en hypertension clinics in northeast Italy. Main outcome measures Echo cardiographic data in relation to WCH status. Patients and methods Mil d hypertensive subjects from the HARVEST (n = 565) who underwent two a mbulatory blood pressure monitorings 3 months apart and M-mode echocar diography, and 95 normotensive control subjects, Results From first am bulatory monitoring, 90 hypertensive subjects were classified as havin g WCH (mean daytime blood pressure <130/80 mmHg). Their 24 h blood pre ssure was similar to that of the normotensive subjects, but their left ventricular mass index was greater. From second ambulatory monitoring , only 38 of the 90 subjects still had WCH, whereas 24 h blood pressur e in the other 52 had risen beyond the limit of WCH. Left ventricular mass index (89.2 +/- 2.4 g/m(2)), wall thickness (18.1 +/- 0.3 mm), an d relative wall thickness (0.359 +/- 0.006%) of the 38 subjects with W CH at both recordings were still greater than those of the normotensiv e subjects (82.4 +/- 1.5 g/m(2), P = 0.02; 17.2 +/- 0.2 mm, P = 0.002; and 0.337 +/- 0.004%, P = 0.025) and similar to those of the 52 subje cts who no longer had WCH (88.5 +/- 2.0 g/m(2), 18.7 +/- 0.2 mm, and 0 .375 +/- 0.005%, all NS), Conclusions Owing to regression toward the m ean, over 50% of the subjects with WCH could no longer be classified a s such from repeated ambulatory monitoring, indicating that the curren t diagnosis of WCH is subject to selection bias, Cardiac remodeling wa s present also in the subjects confirmed to have WCH by repeated blood pressure recording, suggesting that the effect of WCH has an actual i mpact on target organs. I Hypertens 16:977-984 (C) 1998 Lippincott-Rav en Publishers.