Accuracy of point-of-care testing for blood glucose monitoring in critically ill patients:evaluation of glucase oxidase and glucose dehydrogenase methods

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Objective To evaluate the accuracy of point-of-care testing (POCT) for blood glucose monitoring in critically ill patients.Methods Two hundred and forty critically ill patients,of both sexes,aged 20-88 yr,with Acute Physiology and Chronic Health Evaluation Ⅱ score of 1-45,were enrolled.The venous,arterial and capillary blood samples were collected to determine the real-time blood glucose level using glucose oxidase (GOD) and glucose dehydrogenase (GDH) methods.The blood glucose level measured by central laboratory hexokinase method simultaneously was served as standard level.Error Grid analysis (EGA) and Bland-Altman analysis were used to determine accuracy and consistency,respectively.The accuracy of real-time blood glucose levels within the consistent limits was evaluated.Results 1.The results of EGA showed that 98.7 ％,98.3 ％,98.3 ％(GDH method) and 96.2％,96.6％,96.7％ (GOD method) of the difference between venous,arterial and capillary blood glucose levels measured and the standard level were located in the A and B zones,respectively,and 1.2％,1.7％,1.7％ (GDH method) and 2.9％,3.3％,3.3％ (GOD method) in the D zone.0.8％ (GOD method) of the difference between venous blood glucose levels and the standard level were located in the C zone.2.Bland-Altman analysis showed that the difference between the standard level and glucose level measured in blood samples from the vein,artery and capillary.was-0.1,-0.3,-0.2 mmol/L (GDH method) and-0.9,-1.0,-0.9 mmol/L (GOD method),respectively,and the incidence beyond the upper and lower limits of consistency zone was 4.5 ％,6.7 ％,6.6 ％ (GDH method) and 4.6 ％,5.0 ％,7.1％ (GOD method),respectively.The accuracy of venous,arterial and capillary blood glucose levels within the consistent limits was 94.3 ％,92.1％,93.7％ (GOD method) and 96.6％,95.1％,95.5％ (GDH method),respetively.Conclusion The accuracy of POCT for blood glucose monitored by GOD and GDH methods is good in critically ill patients,but it is possible to overestimate the patient's real glucose level. Key words: Critical illness; Blood glucose; Point-of-care systems