Independent Project HCAI 5221

Evaluation of Point of Care Bedside Glucose Monitors for

Use in a Specialty & Transplant Hospital

Mary A. Weidner, BS, MT(ASCP)

BackgroundMethodist Specialty and Transplant Hospital is a 379 bed facility providing a variety of organ transplant servicesA Roche AccuCheck POC device is used post-operatively at our facility to monitor whole blood glucose in the ICU. A positive bias has been observed for the Roche AccuChek whole blood glucose meter (Fig 1 is an example of this observation)A review of the medical literature revealed a number of substances (e.g., maltose, hematocrit, IVIG) can interfere with whole blood glucose meters. This potential for interference and subsequent discordance with central lab methods led to concern by the clinical staff about accuracy of POCT results and exploration of alternative glucose monitors

ObjectivesThrough regression analysis evaluate the accuracy, specificity, connectivity, and clinical performance of alternative POC glucose monitoring devices against the central laboratory for use within Methodist Specialty and Transplant Hospital

Materials and MethodsPrior to testing these devices in a clinical setting, in lab linearity and precision studies were performed (data not shown). Each monitor tested performed acceptably. To assess the potential for interference two glucose meters available at the time (AccuChek and Precision XP) were evaluated in patients typical of our hospital. Arterial whole blood from central lines was taken at the times indicated in Fig 1 and in parallel ran on each meter. In addition these specimens were spun down and the plasma ran on the Vista hexokinase method for comparison. Mean % bias was calculated relative to the Vista reference method. Fig 1 and 2 show the results of this comparison. A Nova StatStrip was acquired at a later time. Studies to evaluate the potential for known interferences such as hematocrit and maltose were assessed by testing samples of 3 different glucose concentrations in which the hematocrit and maltose concentration was adjusted to varying levels (Fig 3). Finally whole blood specimens were spiked with increasing concentrations of glucose and then ran on each glucose monitor. These specimens were subsequently spun down and plasma ran on the Vista hexokinase central laboratory method. Regression analysis was performed to determine concordance between the two methods (Fig 4). The Point of Care team also evaluated connectivity options based on ability to support existing POC tests and the ability to expand as new POC tests are implemented.

Figure 1. Increased Bias Observed with Roche AccuChek. Arterial whole blood measurements were performed post-operatively as a function of time. Panel A shows a mean positive bias of 35% for the Roche AccuChek in a patient administered IVIG. Panel B also demonstrates a positive mean bias (16%) in a patient which underwent liver transplant procedure.

Panel A Panel B

Figure 2. Bias Also Observed with Abbott Precision XP Glucose Monitor. Panel A shows a mean positive bias of 11% when the same specimens from the patient 1 below were ran on the Abbott Precision XP glucose meter. Panel B shows a mean positive bias of 3% when the specimens below for patient 2 are ran on the Abbott Precision XP. Relative to the Roche AccuChek, the Abbott Precision XP had a mean bias ~3x less for patient 1 and ~5x less for Patient 2.

Patient 1: IVIG TherapyAccuCheck vs. Vista

Panel A

Patient 2: Liver Recipient AccuCheck vs. Vista

Panel B

HCT INTERFERENCEFigure 3. Effects of Hct and Maltose on Whole Blood Measurement of Glucose. Three different glucose concentrations were measured under conditions in which the hematocrit

and maltose concentration was adjusted to varying levels. In both instances the Nova StatStrip was not affected. However the AccuChek device was negatively affected by

increasing Hct and positively affected by increasing maltose concentrationsat all glucose levels studied.

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GLUCOSE METERS VS. CENTRAL LAB

Figure 4 a, b, c respectively. Glucose meters vs. central lab. All three glucose meters tested demonstrated strong correlation with the central lab method with R2 values shown. Linearity was somewhat equal between the Abbott Precision Xceed Pro and the Nova StatStrip with a slope of 0.959 to 0.998, respectively. The Roche AcccuCheck demonstrated the highest y-intercept at 20.848.

Figure 4a.

Figure 4b.

Figure 4c.

ConclusionsAll three meters demonstrate good correlation with central lab, however both the Abbott Precision Xceed Pro (R2 = 0.98567) and the Nova StatStrip (R2 = 0.99790), had the acceptable CLSI correlation with slopes closest to 1 and lower y-intercept then the Roche AccuCheck meter.

Future Directions•Future directions will include investigations to evaluate the performance of the Abbott Precision XP in clinical settings. The decision to go with the Abbott XP was made by the MHS system because it was the best overall fit for the entire MHS System and its patient population.

•Electronic Diabetes Flow Record will be utilized to perform “real time” patient treatment, which currently All hospitals have a lag time from result to actual intervention. With this electronic record, once the glucometers go wireless; MHS will be leading the nation in the innovation of patient treatment so that it will no longer will only be about insulin but inclusive of all diabetes treatment.