Validation of the A&D UA-631 (UA-779 Life Source) device for self-measurement of blood pressure and relationship between its performance and large artery compliance

Abstract

Objectives: To determine the accuracy of the UA-631 (UA-779 Life Source for the American market) blood pressure monitor developed by the A&D Company (Toshimi-ku, Tokyo, Japan).

Design: Device evaluation was performed using a new protocol proposed by the Working Group on blood pressure monitoring of the European Society of Hypertension (ESH). Monitor performance was assessed in relation to subjects' gender, age, skinfold thickness, arm circumference, BMI, and elasticity index of large (C1) and small (C2) arteries.

Methods: The A&D recorder was assessed according to the various phases of the protocol. Sequential readings were taken for the main validation test. Outcome was classified according to the criteria of ESH recommendations, which are based on four zones of accuracy differing from the mercury standard by 5, 10, 15 mmHg, or more.

Results: The main validation test was performed in 66 subjects for a total of 198 device measurements. The A&D monitor passed all three phases both for systolic and diastolic blood pressure (SBP and DBP). Mean blood pressure difference between device and observers was 2 +/- 5 mmHg for SBP and 1 +/- 3 mmHg for DBP. The absolute discrepancy between device and observers (4 +/- 4 mmHg for SBP, and 2 +/- 2 mmHg for DBP) was related to age (negatively) and to C1 (positively), but in a multivariable regression analysis only C1 remained a significant independent predictor of the absolute device-observer discrepancy.

Conclusions: These data show that the A&D UA-631 device satisfies the new recommended ESH accuracy levels for both SBP and DBP. Its performance seems to be better in subjects with stiffer arteries.