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

Completed

Conditions: Hypertension

Interventions: Device: Doppler Ankle-Brachial Index measurement
Device: WatchBP Office Ankle-Brachial Index measurement.

Registration Number: NCT01002989

Lead Sponsor: University of Athens

Brief Summary: 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)

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.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 98

Inclusion Criteria

Treated or untreated subjects assessed for hypertension

Exclusion Criteria

Atrial fibrillation
Incompressible ankle arteries

Study & Design

Study Type: OBSERVATIONAL

Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
All eligible patients	Doppler Ankle-Brachial Index measurement	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.
All eligible patients	WatchBP Office Ankle-Brachial Index measurement.	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.

Primary Outcome Measures

Name	Time	Method
Mean Doppler Ankle-Brachial Index	once (cross-sectional)
Watch BP Office Minus Doppler Ankle-Brachial Index Difference	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 Watch BP Office Ankle-Brachial Index	once (cross-sectional)

Secondary Outcome Measures

Name	Time	Method
Agreement Between the Two Methods in Peripheral Artery Disease (PAD) Diagnosis	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.