Journal Article

Indication-specific 6-hour systolic blood pressure thresholds can approximate 24-hour determination of blood pressure control

Lin, Wenjiao, Weber, Cynthia A., Dawson, Jeffrey D., Sezate, Genesis S., Carter, Barry L., Ernst, Michael E., Bergus, George R.

2010

Overview

Ambulatory blood pressure monitoring (ABPM) is an accurate method for evaluating hypertension, yet its use in clinical practice may be limited by availability, cost, and patient inconvenience. The objective of this study was to investigate the ability of a 6-hour ABPM window to predict blood pressure control, based on that of the full 24-hour ABPM session across several clinical indications in a cohort of 486 patients referred for ABPM. Sensitivities and specificities of the 6-hour systolic blood pressure mean to accurately classify patients as hypertensive were determined using a fixed reference point of 130 mmHg for the 24-hour mean. For four common indications in which ABPM was ordered, prediction tables were constructed varying the thresholds for the 6-hour mean to find the optimal value that best predicted the 24-hour hypertensive status as determined from the full 24-hour interval. Using a threshold of 137 mmHg for the indications of borderline hypertension, evaluation of current antihypertensive regimen and suspected white-coat hypertension, sensitivity and specificity ranged from 0.83–0.88 and 0.80–0.88, respectively, for the ability of 6-hour ABPM to correctly categorize hypertensive status. Using 133 mmHg as the threshold for treatment resistance resulted in a sensitivity and specificity of 0.93 and 0.83, respectively. We conclude that a shortened ABPM session of 6 hours can be used to accurately classify blood pressure as controlled or not, based on the results of a 24-hour session. The optimal 6-hour threshold for comparison depends upon indication for referral.