CLINICAL RESEARCH STUDY Discrepancies between Office and Ambulatory Blood Pressure: Clinical Implications José R. Banegas, MD, a,b Franz H. Messerli, MD, c Bernard Waeber, MD, d Fernando Rodríguez-Artalejo, MD, a,b Alex de la Sierra, MD, e Julián Segura, MD, f Alex Roca-Cusachs, MD, g Pedro Aranda, MD, h Luis M. Ruilope, MD f a Department of Preventive Medicine and Public Health, Universidad Autónoma de Madrid, Spain; b CIBER en Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain; c Division of Cardiology, St. Luke’s-Roosevelt Hospital, Columbia University College of Physicians and Surgeons, New York, NY; d Division of Clinical Pathophysiology, Centre Hospitalier Universitaire Vaudois et Université de Lausanne, Switzerland; e Hypertension Unit, Clinic Hospital, Barcelona, Spain; f Hypertension Unit, Doce de Octubre Hospital, Madrid, Spain; g Hypertension Unit, Department of Internal Medicine, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Spain; h Nephrology Department, Hospital Regional Universitario Carlos Haya, Málaga, Spain. ABSTRACT BACKGROUND: Recent trials have documented no benefit from small reductions in blood pressure measured in the clinical office. However, ambulatory blood pressure is a better predictor of cardiovascular events than office-based blood pressure. We assessed control of ambulatory blood pressure in treated hypertensive patients at high cardiovascular risk. METHODS: We selected 4729 patients from the Spanish Ambulatory Blood Pressure Monitoring Registry. Patients were aged 55 years and presented with at least one of the following co-morbidities: coronary heart disease, stroke, and diabetes with end-organ damage. An average of 2 measures of blood pressure in the office was used for analyses. Also, 24-hour ambulatory blood pressure was recorded at 20-minute intervals with a SpaceLabs 90207 device. RESULTS: Patients had a mean age of 69.6 (8.2) years, and 60.8% of them were male. Average time from the diagnosis of hypertension to recruitment into the Registry was 10.9 (8.4) years. Mean blood pressure in the office was 152.3/82.3 mm Hg, and mean 24-hour ambulatory blood pressure was 133.3/72.4 mm Hg. About 60% of patients with an office-pressure of 130-139/85-89 mm Hg, 42.4% with office-pressure of 140-159/90-99 mm Hg, and 23.3% with office-pressure 160/100 mm Hg were actually normotensive, according to 24-hour ambulatory blood pressure criteria (130/80 mm Hg). CONCLUSION: We suggest that the lack of benefit of antihypertensive therapy in some trials may partly be due to some patients having normal pressure at trial baseline. Ambulatory monitoring of blood pressure may allow for a better assessment of trial eligibility. © 2009 Elsevier Inc. All rights reserved. • The American Journal of Medicine (2009) 122, 1136-1141 KEYWORDS: Ambulatory blood pressure; Antihypertensive therapy; Blood pressure control; Clinical trials; Office blood pressure; Treatment goals During the last few years, a number of randomized trials have compared “head-to-head” different antihypertensive drugs. 1-7 Because most of the clinical benefits are con- ferred by the degree of blood pressure (BP) reduction, 8-12 interpretation of the results of these trials might be dif- ficult unless blood pressure control in the treatment arms is similar. 8 Also, and somewhat astonishingly, some recent trials of antihypertensive treatment achieving a small but significant reduction in blood pressure have documented little if any benefit against placebo. 13,14 Of note, in most of these studies, blood pressure at trial entry was only slightly elevated (mean systolic pressure of 140-150 mm Hg, and inclusion of normotensive individuals). Recent studies have shown that out-of-office blood pres- sure, as assessed by 24-hour ambulatory monitoring, predicts Funding: The main funding for the study was obtained from Lacer Spain, SA, through an unrestricted educational grant. Conflict of Interest: None. Authorship: We verify that all authors had access to the data and a role in writing the manuscript. Requests for reprints should be addressed to Luis M. Ruilope, MD, Hyper- tension Unit, Doce de Octubre Hospital, Av. Cordoba s/n, Madrid 28041, Spain. E-mail address: ruilope@ad-hocbox.com 0002-9343/$ -see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.amjmed.2009.05.020