Response to Indices of Blood Pressure Variability and Cardiovascular Risk
We reported that, with the 24-hour blood pressure level in the multivariable-adjusted Cox models, average real variability over 24 hours (ARV24) added only 0.1% to the explained risk of a composite cardiovascular end point.1 Pierdomenico2 requested a similar analysis for the SD over 24 hours weighted for the time interval between consecutive readings (SD24) and the average of the daytime and nighttime SDs weighted for the duration of the daytime and nighttime intervals (SDdn). Results for adding to the basic Cox model first the 24-hour blood pressure alone and next the 24-hour blood pressure plus SD24, SDdn, or ARV24 appear in the Table. In line with our findings for ARV24, adding SD24 or SDdn did not or only weakly improved the risk stratification already provided by the 24-hour blood pressure.
Figure 3 of our article1 emphasizes that the relative contribution of the 24-hour blood pressure level to the 10-year absolute cardiovascular risk was substantially greater than that of ARV24, which in our hands best captured blood pressure variability. In the last sentence of our article’s Perspectives section,1 we made the point that both ARV24 and SDdn are useful measures of blood pressure variability but not SD24. A major problem is that SD24 also reflects the day-night blood pressure difference. Pierdomenico et al3 and other investigators1,4⇓ demonstrated that, for the same SD in distinct blood pressure recordings, ARV24 can be widely different.
Sources of Funding
The European Union (grants IC15-CT98-0329-EPOGH, LSHM-CT-2006-037093, and HEALTH-F4-2007-201550), The Fonds voor Wetenschappelijk Onderzoek Vlaanderen (Ministry of the Flemish Community, Brussels, Belgium) (grants G.0575.06 and G.0734.09), and the Katholieke Universiteit Leuven (grants OT/00/25 and OT/05/49) gave support to the Studies Coordinating Centre in Leuven.
- ↵Hansen TW, Thijs L, Li Y, Boggia J, Kikuya M, Björklund-Bodegård K, Richart T, Ohkubo T, Jeppesen J, Pedersen CT, Dolan E, Kuznetsova T, Stolarz-Skrzypek K, Tikhonoff V, Malyutina S, Casiglia E, Nikitin Y, Lind L, Sandoya E, Kawecka-Jaszcz K, Imai Y, Wang J, Ibsen H, O'Brien E, Staessen JA, for the International Database on Ambulatory Blood Pressure in Relation to Cardiovascular Outcome Investigators. Prognostic value of reading-to-reading blood pressure variability over 24 hours in 8938 subjects from 11 populations. Hypertension. 2010; 55: 1049–1057.
- ↵Pierdomenico SD. Indices of blood pressure variability and cardiovascular risk. Hypertension. 2010; 56: e21.
- ↵Pierdomenico SD, Lapenna D, Di Tommaso R, Di Carlo S, Esposito AL, Di Mascio R, Ballone E, Cuccurullo F, Mezzetti A. Blood pressure variability and cardiovascular risk in treated hypertensive patients. Am J Hypertens. 2006; 19: 991–997.
- ↵Mena L, Pintos S, Queipo NV, Aizpúrua JA, Maestre G, Sulbarán T. A reliable index for the prognostic significance of blood pressure variability. J Hypertens. 2003; 23: 505–511.