Clarke error grid

Error grid 96.8-98.4% Consensus error grid Consensus error grid Clark error grid 97% A... 

GlucoWatch Biographer data for comparison MARD 17-21% Clarke error grid A + B 94% Clarke error grid A 60% ... 

Figure 1.7 Clarke error grid analysis plot of the data of Figure 1.6.

Figure 3.2 The effect of prolonged subcutaneous implantation on biosensor function. Blood glucose values shown in solid circles and glucose sensor values in the continuous lines. The early study (top panel), but not the late study (bottom), shows excellent sensor accuracy and minimal lag between blood glucose and sensed glucose values. MARD (mean absolute relative difference) refers to a sensor accuracy metric. EGA refers to the Clarke error grid analysis accuracy metric.

The different manufacturers publish their own results in their user manuals. Mean absolute relative difference and bias results from the three manufacturers are shown in Table 5.2. The MARD measures indicates the average difference while the direction of the difference and the bias indicates if the differences are uniform or skewed to positive or negative values. The Clarke error grid analysis for the three manufacturers (Table 5.3) shows a wide difference in A zone results between the... 

TABLE 5.4 Guardian RT Clarke Error Grid by Glucose Range... 

TABLE 5.5 FreeStyle Navigator System Clarke Error Grid by Day of Wear... 

In Ref. 36, the likelihood test described above is applied to five pairs of implanted sensors and examined on the Clarke error grid for clinical relevance. The percentage... 

Clarke error grid analysis of a study of 15 diabetic rats showed the percentage of readings that fell into the clinically correct regions (Zones A and B) increased from 92% to 96% when applying the Z-score rejection criteria.38 During the long-term implantation (25 4 days), Z-score calculations removed 32% of the individual sensor data from six fully implanted four-sensor arrays.39... 

Finally, the DT/MH AgFON was evaluated in vivo. A representative Clarke error grid analysis of a single rodent is shown in Figure 15.11. All measurements were taken from a single spot on the implanted DT/MH-functionalized AgFON surface. 

Test results of glucose meters are often compared with results from a reference method and presented in the form of a Clarke error grid that defines zones with different clinical implications. Clarke, WL, Cox, DC, Gonder-Frederick, LA, Carter, W, and Pohl, SL. 1987. Evaluating clinical accuracy of systems for self-monitoring of blood glucose. Diabetes Care 10 622-628. 

Figure 10 NIR-predicted serum glucose levels vs reference assays (see also NIR B in Table 4). Open circles correspond to the calibration (training) set, solid circles to the validation (test) set, and the solid line is the line of identity. A Clarke error grid(3°) is superimposed, distinguishing regions corresponding to clinically safe analytical errors (regions A, B) from analytical errors that would result in dangerously inappropriate clinical decisions (C, D, E). (Adapted from K.H. Hazen, M.A. Arnold, G.W. Small, Measurement of Glucose and Other Analytes in Undiluted Human Serum with Near-infrared Transmission Spectroscopy , Analytica Chimica Acta, 255-267, Vol. 371, 1998, with permission from Elsevier Science.)...

Figure 5.35 Composite Clarke error grid for 18 subjects and 20 sensors. Ninety-five percent of all the points were in zone A of the Clarke error grid, and the MARD was 7.9%.

The Clarke error grid is a standard for evaluating the reliability of glucose sensors in the clinically relevant concentration range (0-450 mg/dL) (27). Data... 

Figure 7. Calibration (O) and validation ( ) plots of glucose in bovine plasma on Clarke error grid. Calibration plot was constructed using 92 data points and validation plot was constructed using 46 data points. Sample was incubated for 2 min in glucose concentrations ranging from 10 - 450 mg/dl with Aex = 785 nm, laser power = 10-30 mW, t= 2 min. RMSEC = 34.3 m dL (1.9 mM) and RMSEP = 83.16 mg/dL (4.62 mM). Reproduced with permission from ref. 10 Copyright 2005 J. Am. Chem. Soc.

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