Response to White-Coat and Masked Hypertension: Selective Elevation of Blood Pressure or an Arbitrarily Partitioned Continuum?
We thank Dr Ben-Dov for considering our data important for understanding the true nature of white-coat and masked hypertension and for agreeing with our conclusion that physicians should be alerted of any blood pressure increase, no matter where and how it is measured.1 We wish to point out, however, that we have by no means ignored the explanation he favors in his letter, that is, that the increased risk of white-coat and masked hypertension may be because of the fact that, as shown in Tables 1 to 3 of our article,2 when one blood pressure is elevated, the others, although in the normal range, are somewhat higher than those of truly normotensive individuals. We have indeed devoted to this explanation (often overlooked in previous studies) a large part of our discussion. Dr Ben-Dov is correct that the statistical significance of a trend may be affected by the extreme group, that is, the one with combined blood pressure elevation, and that the increased risk of white-coat and masked hypertension was in several instances not statistically significant, presumably because of the limited number of fatal events that we could count on in our population. Yet, the progressive increase in risk was nearly always obvious, and elevation in 1 or 2 blood pressures carried a significant increase in risk. Finally, Dr Ben-Dov’s suggestion to adjust data for “in-office” and “out-of-office” blood pressure is a possibility, and we have indeed shown in a previous article3 that this did not cancel the increased prevalence of left ventricular hypertrophy associated with white-coat and masked hypertension. We have grown more critical, however, of excessive use of “adjusting procedures” when dealing with complex and mechanistically interrelated clinical data, because they by no means guarantee that the role of individual factors is clarified and its contribution to a given phenomenon identified.
Ben-Dov IZ. White-coat and masked hypertension: selective elevation of blood pressure or an arbitrarily partitioned continuum? Hypertension. 2006; 48: e8.
Mancia G, Facchetti R, Bombelli M, Grassi G, Sega R. Long-term risk of mortality associated with selective and combined elevation in office, home and ambulatory blood pressure. Hypertension. 2006; 47: 846–853.
Sega R, Trocino G, Lanzarotti A, Carugo S, Cesana G, Schiavina R, Valagussa F, Bombelli M, Giannattasio C, Zanchetti A, Mancia G. Alterations of cardiac structure in patients with isolated office, ambulatory or home hypertension: data from the general population. Circulation. 2001; 104: 1385–1392.