Arkon PRT03831-xxx manual 155

Section 18

Appendix B: Specifications

155

18 Appendix B: Specifications (con’t)

Table 2 is a summary of the statistics that describe how well data from the FreeStyle Navigator system correlates to the results from the reference method. Glucose results from the FreeStyle Navigator system and the corresponding results from the YSI (a total 20362 pairs of data points) in the In- Clinic study were used to determine the correlation.

Figure 1.

(mg/dL)	500			y = x
						A
						A
	400		C	B
		E
	300					B
CM
Navigator	200
		D			D
	100
			C		E
	0
	0	100	200	300	400	500

Table 2. Regression Analysis. FreeStyle Navigator System (mg/dL) vs the YSI (mg/dL)

Slope	0.92
Intercept	14.3 mg/dL
Correlation Coefficient (r)	0.93
N	20362
Range	25 – 533 mg/dL
Overall mean bias	+0.8 mg/dL

YSI Reference (mg/dL)

Table 3a displays the distribution of all the data from the In-Clinic study on the Clarke Error Grid. It breaks the data set into smaller groups based on the glucose value reported by the YSI. For each of these smaller groups, the table shows what percentage of data fall into different zones of the grid.

Table 3a. Accuracy performance at different glucose levels using the Clarke Error Grid Analysis

Reference	Number of	A and B	A	B	C	D	E
Glucose Level	Paired	(%)	(%)	(%)	(%)	(%)	(%)
(mg/dL)	Readings
20-40	22	54.5	54.5	N/A*	N/A*	45.5	0.0
41-80	1295	77.7	55.2	22.5	0.0	22.3	0.0
81-120	3820	99.9	69.5	30.4	0.1	N/A*	N/A*
121-240	11430	99.9	85.4	14.4	0.1	N/A*	0.0
241+	3795	99.5	91.7	7.8	0.0	0.4	0.1
Overall	20362	98.3	81.7	16.7	0.1	1.6	0.0

*N/A means that the Clarke Error Grid does not consider the possibility of these zones in that concentration range.

Table 3b displays the same data as in table 3a on the Continuous Glucose-Error Grid. This is a modified error grid that is designed to evaluate the clinical accuracy of continuous glucose monitoring systems based on both glucose data points in time and the rate of change of glucose.

Table 3b. Accuracy performance at different glucose levels using the Continuous Glucose-Error Grid Analysis

	YSI ≤ 70 mg/dL		70 mg/dL < YSI		YSI > 180 mg/dL			All
Zone			≤180 mg/dL
	N	%	N	%	N	%	N		%
Accurate	369	59.5	10407	98.9	8364	98.6	19140		97.5
Readings
Benign	5	0.8	99	0.9	74	0.9	178		0.9
Errors
Erroneous	246	39.7	22	0.2	41	0.5	309		1.6
Readings
ALL	620	100.0	10528	100.0	8479	100.0	19627		100.0

OVER