Assessment of the risk of the Nova StatStrip glucose meter using the Insulin Dose Error Assessment (IDEA) Grid

Introduction: The Clarke, Parkes and Surveillance error grids are expert opinion based tools developed to assess clinical risk associated with glucose meters. The objective of this study was to assess the clinical risk of the Nova StatStrip® glucose meter using an insulin dosing error grid that expresses glucose error in units of the ‘size of error in insulin dose categories’ which is customizable for local insulin protocols. Materials and Methods: Residual lithium heparin venous whole blood specimens (n=156) from hospitalized adult patients were immediately analyzed using the Nova Statstrip® glucose meter and 100 µL of whole blood was treated with perchloric acid prior to analysis with a traceable isotope dilution mass spectrometry (IDMS), the definitive method for glucose. The clinical accuracy of the Nova StatStrip® glucose meter relative to the IDMS was assessed using the Parkes, Surveillance Error and IDEA error grids. For the IDEA grid, the effect of 0.5 mg/dL differences between methods on the size of insulin dose category error was determined by simulation using the protocol for critically ill patients (Karon et al, 2010). Patient data was plotted on the error grid to indicate the extent that observed glucose results are expected to affect changes of insulin dose. Results: Parkes error grid analysis revealed that zone A contained 98.1% (153/156) of the Statstrip® results and zone B 1.9% (3/156). With the Surveillance error grid, 154/156 results were within the assessable range and 93.5% (144/154) indicated no degree of clinical risk. The remaining 6.5% (10/154) were within the “slight” category of clinical risk.
Conclusions: The clinical risk of inappropriately administering insulin with the Nova Statstrip® glucose meter was minimal (100% of results within +/- 2 insulin dose categories). The IDEA error grid analysis is a useful and adaptable tool to assess clinical applications of glucose meters.