Comparison of Different Automated Office Blood Pressure Measurement Devices: Evidence of Nonequivalence and Clinical Implications

Background: Automated office blood pressure (AOBP) measuring devices are increasingly recommended as preferred blood pressure (BP) diagnostic tools, but it is unclear how they compare and how clinical environments impact their performance. Methods: This prospective randomized factorial parallel 4-group study compared BP estimates by BpTRU (VSM MedTech, Vancouver, BC, Canada) and Omron HEM 907 (Omron Healthcare, Kyoto, Japan) devices in closed vs open areas. Patients diagnosed with hypertension were recruited during office visits. After baseline open-room AOBP measurement with the BpTRU, patients had a second BP measurement with either the BpTRU or HEM 907 in either open or closed areas. Absolute BP levels and differences between the first and second measurements were compared. Diagnostic performance was also assessed. Results: Two hundred fifty-eight patients were studied. Their mean age was 66.2 +/- 12.0 years, and 62% were men. The mean of first AOBP estimates was 127.4/73.3 mm Hg. Analyses of subsequent measurements revealed no influence of open or closed areas on BP means and diagnostic performance. Conversely, the Omron HEM 907 exceeded BpTRU systolic BP measurements by 4.6 mm Hg (< 0.01) in closed areas and by 3.9 mm Hg (< 0.01) in open areas. The discrepancy between devices was amplified at lower BP levels. Conclusions: Although different areas did not influence BP estimates, the Omron HEM 907 significantly exceeded BpTRU measurements on average and especially at lower BP levels. These differences should be considered when interchanging devices and could have clinical decision impacts in a population of patients treated for hypertension. Our results support the constant use of only 1 device type in a given clinic.