Objectives: To determine the accuracy of the A&D UB-511 (UB-512) oscillometric wrist-cuff device for self-measurement of blood pressure, the only difference between the two devices being the size of storage memory.
Methods: Device evaluation was performed according to the modified British Hypertension Society protocol released in 1993. Eighty-five study participants with characteristics outlined in the British Hypertension Society protocol were recruited among those attending our out-patient clinic. The device was evaluated according to the various steps of the protocol. The non-dominant arm was used for blood pressure measurement. To maintain the wrist at cardiac level during validation, the arm was kept horizontal at the mid-sternum level and supported by a soft table. The wrist was kept extended. Sequential readings were taken for the main validation test. Outcome was classified according to the criteria of the British Hypertension Society recommendations, which are based on four strata of accuracy differing from the mercury standard by 5, 10 and 15 mmHg, or more.
Results: The device achieved a British Hypertension Society grade B for systolic and a grade B for diastolic blood pressure. The device tended to overestimate arm blood pressure, the mean difference (+/-1 SD) between device and observers being 4.3+/-8.7 mmHg for systolic blood pressure and 3.7+/-8.1 mmHg for diastolic blood pressure for observer 2, and 4.4+/-8.6 mmHg for systolic blood pressure and 3.8+/-7.9 mmHg for diastolic blood pressure for observer 1. In a logistic regression analysis, age was the sole predictor of an achieved difference between device and mercury column by 5 mmHg or less (hazard ratio 1.020; 95% confidence interval 1.003-1.04; P=0.024).
Conclusions: These data show that the A&D UB-511 (UB-512) device satisfies the British Hypertension Society recommendations with a grade B/B. The device tends to overestimate cuff blood pressure and its accuracy increases with age.