Use of stabilized whole blood for glucose proficiency testing at point-of-care sites

In large institutions, patients are often cared for on multiple units, and their glucose test results can come from a variety of sources. As such, it is important to ensure comparability of glucose results between multiple point-of-care devices, as well as between a point-of-care device and the central laboratory. In addition, it is important to periodically monitor the glucose meters beyond daily quality control to ensure that there are no testing problems. In this study, we investigate the use of a commercially manufactured linearity material, Sugar-Chex Linearity, for these purposes. The material was analyzed on 189 glucose meters throughout the institution, and the accuracy of the mean, precision, as well as stability were evaluated at 5 levels of glucose concentration (33, 123, 235, 326, 430 mg/dL). The accuracy ranged from 4.6% to 12.8% difference from the assigned value, whereas the precision (percentage of coefficient of variance) ranged from 5.3% to 8.9%; both parameters were acceptable when compared to current guidelines. The material was shown to have a closed-vial stability well beyond 100 days at a refrigerated temperature, but more importantly, from the clinical perspective, the open-vial stability of 14 days at room temperature was achieved.