Diagnostic accuracy of home vs. ambulatory blood pressure monitoring in untreated and treated hypertension

Abstract

Several studies with relatively small size and different design and end points have investigated the diagnostic ability of home blood pressure (HBP). This study investigated the usefulness of HBP compared with ambulatory monitoring (ABP) in diagnosing sustained hypertension, white coat phenomenon (WCP) and masked hypertension (MH) in a large sample of untreated and treated subjects using a blood pressure (BP) measurement protocol according to the current guidelines. A total of 613 subjects attending a hypertension clinic (mean age 53±12.4 (s.d.) years, men 57%, untreated 59%) had measurements of clinic BP (three visits, triplicate measurements per visit), HBP (6 days, duplicate morning and evening measurements) and awake ABP (20-min intervals) within 6 weeks. Sustained hypertension was diagnosed in 50% of the participants by ABP and HBP (agreement 89%, κ=0.79), WCP in 14 and 15%, respectively (agreement 89%, κ=0.56) and MH in 16% and 15% (agreement 88%, κ=0.52). Only 4% of the subjects (27/613) showed clinically significant diagnostic disagreement with BP deviation >5 mm Hg above the diagnostic threshold (for HBP or ABP). By taking ABP as reference, the sensitivity, specificity, positive and negative predictive value of HBP in detecting sustained hypertension were 90, 89, 89 and 90%, respectively, WCP 61, 94, 64 and 94% and MH 60, 93, 60 and 93%. Similar diagnostic agreement was found in untreated and treated subjects. HBP appears to be a reliable alternative to ABP in the diagnosis of hypertension and the detection of WCP and MH in both untreated and treated subjects.