Response to Out-of-Office Blood Pressure Control Among Treated Subjects
We thank Obara et al1 for their interest in our article.2 We agree with them that given that many antihypertensive drugs do not seem to encompass a full 24-hour period and that a high percentage of subjects with hypertension in our study were on a morning-only therapeutic regimen, BP at nighttime would be expected to be less sufficiently controlled than that in the daytime. In our study on 12 897 treated patients with hypertension in a primary care setting in Spain, office systolic blood pressure (BP)/diastolic BP was 149.4/86.8 mm Hg (±19.3/11.6 mm Hg), average ambulatory daytime systolic blood pressure (BP)/diastolic BP was 133.1/78.7 mm Hg (±14.7/10.5 mm Hg), and average ambulatory nighttime systolic blood pressure (BP)/diastolic BP was 122.0/68.3 mm Hg (±16.6/10.4 mm Hg). Office BP control (<140/90 mm Hg) was 23.6% (95% CI: 22.9% to 24.3%), daytime control (<135/85 mm Hg) was 51.6% (95% CI: 50.7% to 52.5%), and nighttime control (<120/70 mm Hg) was 40.1% (95% CI: 39.3% to 40.9%). Although BP control at night was lower than daytime BP control, it was still quite higher than office BP control. Therefore, in our study, control of hypertension using ambulatory BP monitoring outside medical settings is much better than that evidenced in the office.
Thus, the discrepancy between the 2 studies does not seem to rely only on these day/night differences in BP control, but rather on difference in the study methods, the time that the BP measurements were taken (multiple measurements in the early morning in the Japanese study and multiple determinations during the day in the Spanish study), and the different techniques to assess BP control (home self-measurement of BP versus ambulatory BP monitoring).2,3 In addition, in the Japanese study, BP control at home based on the average of morning and evening BP (a situation closer to ours, that is the average of ambulatory measurements during the awake period) was higher (42.4%) than that based on only morning BP (33.7%), and controlled office BP (42%) was now slightly lower than controlled home BP (average of morning and evening; 42.4%).3,4 Finally, in a population study in Italy, a higher BP control was also reported among treated subjects when using home self-measured BP (28%) compared with office BP (21%).5
We thank all of those physicians and members of the Spanish Society of Hypertension ABPM Registry who participated in this study (http://www.cardiorisc.com).
Sources of Funding
Main funding was obtained from Lacer Spain, SA, through an unrestricted educational grant. The funding body had no role in study design, analysis and interpretation of data, writing the report, or the decision to submit the article for publication.
Obara T, Ohkubo T, Metoki H, Asayama K, Kikuya M, Imai Y. Out-of-office BP control among treated subjects. Hypertension. 2007; 49: e40–e41.
Banegas JR, Segura J, Sobrino J, Rodríguez-Artalejo F, Sierra A, Cruz JJ, Gorostidi M, Sarría A, Ruilope LM. Effectiveness of blood pressure control outside the medical setting. Hypertension. 2007; 49: 62–68.
Obara T, Ohkubo T, Kikuya M, Asayama K, Metoki H, Inoue R, Oikawa T, Komai R, Murai K, Horikawa T, Hashimoto J, Totsune K, Imai Y, and the J-HOME Study Group. Prevalence of masked uncontrolled and treated white-coat hypertension defined according to the average of morning and evening home blood pressure value: from the Japan Home versus Office Measurement Evaluation Study. Blood Press Monit. 2005; 10: 311–316.