Correlation of blood pressure readings from 6-hour intervals with the daytime period of 24-hour ambulatory blood pressure monitoring in pediatric patients

J Clin Hypertens (Greenwich). 2012; 14:396–400. ©2012 Wiley Periodicals, Inc.Shorter‐interval (6‐hour) ambulatory blood pressure monitoring (ABPM) has been shown to correlate well with 24‐hour ABPM in adults, but this has not been studied in children. The authors selected 131 patients aged 9 to 18 who underwent 24‐ABPM from 2000–2008. Six‐hour intervals beginning at different start times were compared with the daytime and 24‐hour period, with subset analysis for normotensive and hypertensive patients. Concordance correlation coefficients (CCCs) were used to assess for agreement. Among normotensive patients, the mean difference between daytime and 6‐hour intervals ranged from −0.1 mm Hg to 0.0 mm Hg for diastolic blood pressure (DBP) and −1.1 mm Hg to 0.6 mm Hg for systolic blood pressure (SBP) with CCCs of 0.88 to 0.93 for DBP and 0.93 to 0.96 for SBP. For hypertensive patients, mean difference ranged from −0.6 to 1.3 mm Hg for DBP and −0.8 to 1.1 mm Hg for SBP with CCCs of 0.89 to 0.98 for DBP and 0.86 to 0.95 for SBP. Shorter‐interval monitoring correlates significantly with full daytime monitoring in children, allowing for assessment of blood pressure with improved convenience.

Hypertension is one of the leading health care problems in the United States. The incidence of hypertension in children prior to the past decade was 1% to 3%. Recent reports confirm an increase in the average blood pressure (BP) in children with a prevalence of hypertension as high as 4.5% in school‐aged children. ¹ Currently, studies evaluating end organ structures demonstrate hypertension as a risk factor for development of left ventricular hypertrophy ² and carotid artery intimal‐medial thickness. ³ Clinic BP (CBP) is the standard for measuring BP in the office; however, ambulatory BP monitoring (ABPM) is becoming the preferred standard for evaluation of children with suspected hypertension. The indications for use of an ABPM device continue to grow and prompted the American Heart Association (AHA) in 2008 to publish a scientific statement providing guidelines on the use and the interpretation of ABPM in the pediatric population. ⁴ One indication for ABPM includes identifying children at greater risk for end organ damage. The ABPM results are a stronger predictor of hypertension‐associated target organ damage compared with CBP. ⁵ , ⁶ , ⁷ The 2008 AHA scientific statement outlines utilization of 24‐hour ABPM. Many families may find 24‐hour monitoring too burdensome or too costly. As such, one option is to order a shorter interval of monitoring. To date, nothing in the literature has provided evidence on the efficacy of shorter intervals of monitoring for the diagnosis of hypertension among children. Several studies have evaluated shorter intervals among the adult population. Ernst and colleagues ⁸ found that 6‐hour monitoring can approximate mean 24‐hour BP results; however, it does not provide information about circadian variations. Graves and colleagues ⁹ report 6‐hour monitoring as comparable to accurate office measurements without the limitations of poor reproducibility and observer bias. Two older studies ¹⁰ , ¹¹ concluded that 3 or 4 readings per hour during a shorter interval correlated with mean daytime pressures by 24‐hour ABPM.Given the option of 6‐hour ABPM at our institution and the recommendations for the use of 24‐hour monitoring, the evaluation of the concordance between the shorter and longer intervals could provide guidance for clinicians as well as increase power of future research studies on ABPM in children. The aim of this study was to determine whether mean and median systolic BP (SBP) and diastolic BP (DBP) from a 6‐hour daytime interval correlate with statistical significance with the mean and median daytime and 24‐hour SBP and DBP among pediatric patients who have undergone 24‐ABPM.