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Validation of WatchBP Office Ankle-brachial Index (ABI) Function (ABI)

This study has been completed.
Information provided by (Responsible Party):
George S. Stergiou, University of Athens Identifier:
First received: October 27, 2009
Last updated: January 20, 2012
Last verified: January 2012

Measurement of the ankle-brachial index (ABI) with the oscillometric device WatchBP Office will be assessed compared to the reference method (Doppler).

Ninety three adult subjects assessed for hypertension, treated or untreated, with complete study data were included. Data on the presence of cardiovascular (CV) disease and classical CV risk factors were recorded.

All the ABI measurements of each individual participant will be performed by the same observer in a randomized order (concerning Doppler and WatchBP)

Condition Intervention
Hypertension Device: Doppler Ankle-Brachial Index measurement Device: WatchBP Office Ankle-Brachial Index measurement.

Study Type: Observational
Study Design: Observational Model: Case-Only
Time Perspective: Cross-Sectional
Official Title: Assessment of the Oscillometric Measurement of the Ankle-brachial Index (ABI) With WatchBP Office ABI Device.

Further study details as provided by George S. Stergiou, University of Athens:

Primary Outcome Measures:
  • Watch BP Office Minus Doppler Ankle-Brachial Index Difference [ Time Frame: once (cross-sectional) ]
    The validation process consisted of two parts: (i) measurement validation, which compared Doppler and Watch BP Office ABI values and assessed their association, and (ii) clinical validation, which compared the diagnosis of peripheral artery disease (PAD) by the two methods and assessed the association of Watch BP Office and Doppler ABI values with cardiovascular risk factors.

  • Mean Doppler Ankle-Brachial Index [ Time Frame: once (cross-sectional) ]
  • Mean Watch BP Office Ankle-Brachial Index [ Time Frame: once (cross-sectional) ]

Secondary Outcome Measures:
  • Agreement Between the Two Methods in Peripheral Artery Disease (PAD) Diagnosis [ Time Frame: Once (cross-sectional) ]
    This outcome measure represents what percentage of the patients diagnosed with PAD using Doppler ABI method (reference method) were diagnosed with PAD using WatchBP Office ABI method. It also represents in what percentage of the patients in whom PAD was excluded with Doppler ABI method (reference method), PAD was excluded using WatchBP Office ABI method as well.

Enrollment: 98
Study Start Date: June 2009
Study Completion Date: June 2010
Primary Completion Date: April 2010 (Final data collection date for primary outcome measure)
Groups/Cohorts Assigned Interventions
All eligible patients

Subjects assessed for hypertension, were subjected to the measurement of ankle brachial index (ABI) by two methods:

  1. Doppler
  2. WatchBP Office oscillometric The order for performing the two methods was randomized.
Device: Doppler Ankle-Brachial Index measurement
Measurement of the Ankle-Brachial Index by Doppler.
Device: WatchBP Office Ankle-Brachial Index measurement.
Measurement of Ankle-Brachial Index by WatchBP Office device.

Detailed Description:

All study measurements were performed under standardized conditions in a quiet examination room with 10 min rest in the supine position before measurements. Ankle-brachial index (ABI) was measured manually by Doppler and automatically by the oscillometric device in randomized order by a single investigator. Manual Doppler ABI was measured according to the American Heart Association guidelines using a continuous wave Doppler device (Hadeco Bidop ES-100V3, Kawasaki, Japan) with a 8 MHz probe. Systolic blood pressure was defined with a standard mercury sphygmomanometer by the first Doppler flow signal while deflating the cuff from a suprasystolic level in brachial, dorsalis pedis and posterior tibial arteries. Systolic pressure was determined sequentially for brachial, dorsalis pedis and posterior tibial arteries for each side and ABI was calculated for each leg by dividing the highest ankle pressure to the highest arm pressure. Automated ABI measurement was performed using a validated oscillometric blood pressure monitor designed for professional use in the office (WatchBP Office device; Microlife, Widnau, Switzerland). This device allows automated simultaneous both arms or arm and leg blood pressure measurements and thereby the calculation of ABI. The ABI results are displayed on the device screen.

The study protocol included three steps: (i) an introductory familiarization automated ABI measurement, (ii) three simultaneous oscillometric both arms blood pressure measurements; in case of a consistent inter-arm difference ≥12 mmHg, the arm with the higher blood pressure was selected for the subsequent oscillometric ABI measurements (otherwise the right arm was used) and (iii) Doppler and automated ABI measurement in randomized order; Doppler ABI was measured once, whereas automated ABI calculation included triplicate simultaneous arm-leg measurements performed for each side. The occurrence of five sequential oscillometric errors was defined as a failure of the oscillometric device to measure ABI.


Ages Eligible for Study:   25 Years to 85 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Sampling Method:   Probability Sample
Study Population
Subjects assessed for hypertension including those with other cardiovascular risk factors

Inclusion Criteria:

  • Treated or untreated subjects assessed for hypertension

Exclusion Criteria:

  • Atrial fibrillation
  • Incompressible ankle arteries
  Contacts and Locations
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Please refer to this study by its identifier: NCT01002989

Hypertension Center, Sotiria Hospital
Athens, Greece, 11527
Sponsors and Collaborators
University of Athens
Principal Investigator: George S Stergiou, Assoc. Prof. Hypertension Center, University of Athens, Greece
  More Information

Responsible Party: George S. Stergiou, Associate Professor of Medicine and Hypertension, University of Athens Identifier: NCT01002989     History of Changes
Other Study ID Numbers: Microlife ABI
Study First Received: October 27, 2009
Results First Received: August 23, 2010
Last Updated: January 20, 2012

Keywords provided by George S. Stergiou, University of Athens:
ankle brachial index
WatchBP Office
oscillometric measurement processed this record on September 19, 2017