Algorithm for diagnosing hypertension using out-of-office blood pressure measurements

Abstract

The authors developed and validated a diagnostic algorithm using the optimal upper and lower cut-off values of office and home BP at which ambulatory BP measurements need to be applied. Patients presenting with high BP (≥140/90 mm Hg) at the outpatient clinic were referred to measure office, home, and ambulatory BP. Office and home BP were divided into hypertension, intermediate (requiring diagnosis using ambulatory BP), and normotension zones. The upper and lower BP cut-off levels of intermediate zone were determined corresponding to a level of 95% specificity and 95% sensitivity for detecting daytime ambulatory hypertension by using the receiver operator characteristic curve. A diagnostic algorithm using three methods, OBP-ABP: office BP measurement and subsequent ambulatory BP measurements if office BP is intermediate zone; OBP-HBP-ABP: office BP, subsequent home BP measurement if office BP is within intermediate zone and subsequent ambulatory BP measurement if home BP is within intermediate zone; and HBP-ABP: home BP measurement and subsequent ambulatory BP measurements if home BP is within intermediate zone, were developed and validated. In the development population (n = 256), the developed algorithm yielded better diagnostic accuracies than 75.8% (95%CI 70.1-80.9) for office BP alone and 76.2% (95%CI 70.5-81.3) for home BP alone as follows: 96.5% (95%CI: 93.4-98.4) for OBP-ABP, 93.4% (95%CI: 89.6-96.1) for OBP-HBP-ABP, and 94.9% (95%CI: 91.5-97.3%) for HBP-ABP. In the validation population (n = 399), the developed algorithm showed similarly improved diagnostic accuracy. The developed algorithm applying ambulatory BP measurement to the intermediate zone of office and home BP improves the diagnostic accuracy for hypertension.