410 C linicians who care for children and adolescents are now facing changes in hypertension, which include new methods for measuring blood pressure (BP) and assessing associated cardiovascular risk factors and target organ damage. Although conventional BP should be used as a reference method for measuring BP and diagnosing hypertension, ambulatory BP monitoring (ABPM) has been introduced into the pediatric population. According to European and American recommendations, ABPM is now increasingly recognized as being a valuable tool in the diagnosis and management of hypertension in children and adolescents. 1–3 Longitudinal studies with repeated measurements have shown that ABPM is prognostically useful for some pathological conditions. 4,5 The potential role of ABPM in the identification of children who are at greatest risk to develop hypertension, for whom targeted prevention programs are expected to be most beneficial, has not been assessed. Masked hypertension, elevated ambulatory BP in the presence of normal conventional BP, is a condition that, in adults, has been associated with organ damage 6 and cardiovascular risk, similar to that for sustained hypertension (both conventional and ambulatory hypertension). 7–9 In childhood, masked hypertension has received little attention, despite a prevalence of ≈10%; it persists in 40% of the subjects and has been associated with left ventricular hypertrophy. 10–13 If an elevation in ambulatory BP precedes the development of sustained hypertension, further knowledge of the risk factors associated with this BP increase can be valuable in the management of hypertension in children and adolescents. To address this issue, we performed a long-term follow-up study assessing how sustained hypertension develops over time in healthy, masked hypertensive youths. The potential sex dimorphism in the incidence and timing of the development of hypertension has been analyzed. Methods This is an extension of a previous follow-up report 12 starting in November 1990 with a total of 10 617 person-months. We enrolled Abstract—The risk and factors related to the development of hypertension among healthy youths with elevated ambulatory and normal conventional blood pressure, masked hypertension, have not been established. We performed a long-term follow-up study assessing how hypertension develops over time in healthy, masked hypertensive youths. The potential sex dimorphism in the incidence and timing of the development of hypertension has been analyzed. In a long-term follow- up study (median follow-up, 36 months), we enrolled 272 healthy conventional normotensive youths (aged 6–18 years; 55.8% girls) of whom 39 had masked hypertension at baseline. Development of sustained hypertension (hypertension in both conventional and ambulatory measurement) was recorded. The daytime systolic blood pressure increased from baseline to last available follow-up in boys (3.5 mm Hg; P<0.001) but not in girls (0.7 mm Hg; P=0.23), leading to a significant between-sex difference (P=0.0022). The incidence of sustained hypertension was 7.0/100 subjects/y (n=12) in masked hypertensives and 0.6/100 subjects/y (n=4) in normotensives. Masked hypertensive boys more frequently proceeded to sustained hypertension as compared with masked hypertensive girls (50.0% versus 17.4%; P=0.041). Masked hypertension at baseline (hazard ratio, 15.6; 95% confidence interval, 4.91–49.7; P<0.0001) and male sex (hazard ratio, 3.25; 95% confidence interval, 1.12–9.39; P=0.0295) were independent factors associated with the incidence of sustained hypertension during the follow-up. In youth, masked hypertension is a precursor of sustained hypertension. The risk of developing sustained hypertension is higher in boys than it is for girls. The fact that masked hypertension is not prognostically innocent increases the importance of the diagnosis at an early age. (Hypertension. 2013;62:410-414.) Key Words: ambulatory blood pressure monitoring ■ child ■ hypertension ■ masked hypertension ■ sex dimorphism Received April 10, 2013; first decision April 30, 2013; revision accepted May 6, 2013. From the Pediatric Department, Consorcio Hospital General, University of Valencia (E.L., M.I.T., J.A.); CIBER Physiopathology Obesity and Nutrition (CB06/03), Institute of Health Carlos III, Madrid, Spain (E.L., M.I.T., J.A., J.R.); Division of Hypertension and Cardiovascular Rehabilitation, Department of Cardiovascular Services, Studies Coordinating Centre, University of Leuven, Leuven, Belgium (L.T. , J.A.S.); Department of Epidemiology, Maastricht University, Maastricht, The Netherlands (J.A.S.); and Hypertension Clinic, Hospital Clinico, INCLIVA, University of Valencia, Valencia, Spain (J.R.). This paper was sent to Robert Carey, Consulting editor, for review by expert referees, editorial decision, and final disposition. Correspondence to Empar Lurbe, Department of Pediatrics, Consorcio Hospital General, University of Valencia, Avda Tres Cruces s/n, 46014 Valencia, Spain. E-mail empar.lurbe@uv.es Sexual Dimorphism in the Transition From Masked to Sustained Hypertension in Healthy Youths Empar Lurbe, Lutgarde Thijs, Maria Isabel Torro, Julio Alvarez, Jan A. Staessen, Josep Redon © 2013 American Heart Association, Inc. Hypertension is available at http://hyper.ahajournals.org DOI: 10.1161/HYPERTENSIONAHA.113.01549 Sexual Dimorphism in Masked Hypertensive Youth by guest on April 9, 2017 http://hyper.ahajournals.org/ Downloaded from