Comparative performance assessment of point-of-care testing devices for measuring glucose and ketones at the patient bedside

Abstract

Point-of-care (POC) testing devices for monitoring glucose and ketones can play a key role in the management of dysglycemia in hospitalized diabetes patients. The accuracy of glucose devices can be influenced by biochemical changes that commonly occur in critically ill hospital patients and by the medication prescribed. Little is known about the influence of these factors on ketone POC measurements. The aim of this study was to assess the analytical performance of POC hospital whole-blood glucose and ketone meters and the extent of glucose interference factors on the design and accuracy of ketone results. StatStrip glucose/ketone, Optium FreeStyle glucose/ketone, and Accu-Chek Performa glucose were also assessed and results compared to a central laboratory reference method. The analytical evaluation was performed according to Clinical and Laboratory Standards Institute (CLSI) protocols for precision, linearity, method comparison, and interference. The interferences assessed included acetoacetate, acetaminophen, ascorbic acid, galactose, maltose, uric acid, and sodium. The accuracies of both Optium ketone and glucose measurements were significantly influenced by varying levels of hematocrit and ascorbic acid. StatStrip ketone and glucose measurements were unaffected by the interferences tested with exception of ascorbic acid, which reduced the higher level ketone value. The accuracy of Accu-Chek glucose measurements was affected by hematocrit, by ascorbic acid, and significantly by galactose. The method correlation assessment indicated differences between the meters in compliance to ISO 15197 and CLSI 12-A3 performance criteria. Combined POC glucose/ketone methods are now available. The use of these devices in a hospital setting requires careful consideration with regard to the selection of instruments not sensitive to hematocrit variation and presence of interfering substances.

Keywords: glucose; ketones; performance evaluation; point-of-care testing.

Figure 1.

Method comparison between reference method and beta hydroxybutyrate concentrations measured by StatStrip (A) and Optium (B) (device 1 closed symbols, device 2 open symbols).

Figure 2.

Bias distribution for glucose method correlation data: Difference of glycemia values between each POCT system (A StatStrip, B Optium, and C Accu-Chek) and the reference method plotted against the reference method, with solid lines representing ISO 15197 2013 and broken lines representing CLSI POCT 12-A3 limits.

Figure 3.

Influence of varying levels of hematocrit on beta hydroxybutyrate (BHB) and glucose values. (A) BHB values measured with StatStrip and Optium for 3 different levels of BHB samples. (B) Glucose values measured with StatStrip, Optium, and Accu-Chek for 3 different levels of glucose samples.

Figure 4.

Influence of acetaminophen, acetoacetate, and ascorbic acid on the beta hydroxybutyrate (BHB) values measured with StatStrip and Optium for 3 different levels of BHB samples

Figure 5.

Influence of acetaminophen, ascorbic acid, galactose, maltose, uric acid, and sodium on the glucose values measured with StatStrip, Optium, and Accu-Chek for 3 different levels of glucose.