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Performance evaluationcobas b 123 POC system

IntroductionThis proof-of-performance white paper demonstrates that the cobas b 123 POC (point-of-care) system is as true and accurate in its measurement of 17 critical care parameters (see below) as well-established and widely used analyzers, such as the cobas b 221 ana-lyzer, and the cobas 6000 analyzer series. In order to demonstrate this, the document details the externally validated performance evaluations conducted with this POC system in order that potential users can have complete confidence that the results obtained for the critical care parameters assessed using this system are equivalent to those obtained with other well-rec-ognised, widely-used analyzers.

17 parameters evaluated with the cobas b 123 POC

system: pH, blood gas (BG: pO2, pCO2), electrolytes

(ISE: Na, K, Cl, Ca), metabolites (Glu and Lac), COOX

(hematocrit (Hct), total hemoglobin (tHb), oxygen

saturation (SO2), hemoglobin derivates (O2Hb, HHb,

COHb, MetHb)) and bilirubin (total).

Key conclusionsThe acceptance criteria for “trueness” and “accuracy” and the acceptance criteria “repeatability” and “intermediate precision” with all sites combined were fulfilled. These externally validated performance evalu-ations confirm that the results obtained with the cobas b 123 POC system for 17 commonly assessed critical care parameters are as true and accurate as those obtained from well-recognized and widely used analyzers, such as the cobas b 221 analyzer – widely regarded as the ‘gold standard’ BGE – and the cobas 6000 analyzer series. The cobas b 123 POC system is an attractive and proven solution for BGE at the point of care, designed for performance at low risk to the hospital.

* For investigational use only in the U.S. CAUTION – Investigational device limited by Federal (or United States) Law to investigational use – The performance characteristics of this product have not been established.Not available in the U.S. pending FDA clearance.

COBAS, COBAS B, COBAS C and LIFE NEEDS ANSWERSare trademarks of Roche.

©2011 Roche

Roche Diagnostics Ltd.CH-6343 RotkreuzSwitzerlandwww.cobas.com

SummaryThese externally validated performance evaluations confirm that the results obtained with the cobas b 123 POC system for 17 commonly assessed critical care parameters are as true and accurate as those obtained from well-recognized and widely used ana-lyzers, such as the cobas b 221 analyzer – widely regarded as the ‘gold standard’ BGE – and the cobas 6000 analyzer series.

The cobas b 123 POC system is an attractive and proven solution for BGE at the point of care, designed for performance at low risk to the hospital.

Overview of methods for external proof of per-formance evaluations performed for the cobas b 123 POC system The objective of the external performance evaluation studies was to investigate the performance of cobas b 123 POC system against widely-used and validated analyzers.

Performance evaluation study:a. Method comparisons of the cobas b 123 POC sys-

tem with the cobas b 221 POC system for pH, pCO2, pO2, Na, K, Cl, Ca, Hct, O2Hb, HHb, COHb, MetHb, tHb and SO2, and compared with cobas 6000 ana-lyzer series for glucose and lactate. These were per-formed externally at six sites in Europe [see below] (200 residual samples per lot; 100 per site and lot).

b. Determination of the intermediate precision of the QC results (daily quality control) over 21 days per-formed externally at six sites in Europe for three different lots at the same test sites [Note; this excluded bilirubin].

The six European evaluation sites were: Ludwigshafen, Hamburg, Graz, Zwolle, Göteborg and Cambridge.

External performance evaluation study, bilirubin: a. Method comparisons of the cobas b 123 POC sys-

tem for bilirubin compared with the cobas c 501 module (part of the cobas 6000 analyzer series) performed externally at three US sites (see below).

b. Determination of the intermediate precision of the QC results (daily quality control) over 21 days per-formed externally in three US sites.*

The three US evaluation sites were: Galveston, TX, Louisville, KY and San Diego, CA.

Additional information on the studies• Heparinisedarterialorvenouswholebloodsamples

were used throughout and fresh arterial, venous or capillary lithium heparin blood samples for the bilirubin evaluation.

• Fordeterminationofresultswithinthecobas b 123 POC system, 150μL samples were required unless otherwise stated.

• Qualitycontrolswereperformedoneachmeasur-ing day of the separate study phases. Samples were measured with both of the used sensor cartridge lots in three different QC levels over 21 days in duplicate determinations (Intermediate precision; daily quality control). In situations where over 21 measuring days were needed, they were tested twice daily once only.

• Afamiliarisationphasewasperformedpriortothestudies with one lot only to ensure that the study operators were suitably familiar with the handling and procedures of the new cobas b 123 POC analyser.

Results for each of the 17 parameters assessed externally for the cobas b 123 POC system in external proof of performance evaluationsThe following pages summarise the main results obtained in the performance evaluations when each of the 17 parameters [see page 1] analyzed with the cobas b 123 POC system were compared against the reference analyzer [as stated within the results of each parameter].

Parameter: pHReference analyzer: cobas b 221 POC systemn = 691, slope = 0.99, intercept = 0.08, r = 0.99, median absolute bias = 0.009, accuracy 100 %

Range Trueness Accuracy (95 %)

lower limit upper limit at lower limit at upper limit at lower limit at upper limit

6.5 7.1 0.05 0.03 0.13 0.07

7.1 7.6 0.03 0.04 0.07 0.08

7.6 8 0.04 0.06 0.08 0.18

Table 1. Acceptance criteria for pH method comparison with blood samples outside the typical range

7.0

7.1

7.2

7.3

7.4

7.5

7.6

7.7

7.8

7.9

8.0

7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 8.0

pH 1

Pot

enti

omet

ryco

bas

b 12

3 P

OC

sys

tem

pH 1 Potentiometrycobas b 221 POC system

Y –

X

pH 1 Potentiometrycobas b 221 POC system

-0.100

-0.050

0.000

0.050

0.100

7.0 7.2 7.4 7.6 7.8 8.0

P/B Regression

Y = 0.991

X = + 0.078

md(95) = 0.015

N = 691 r = 0.9865

t = 0.8943

Identity (x=y) Accuracy-limit

Figure 1. Trueness overall and accuracy overall: pH

Key point: The cobas b 123 POC system was shown to be equivalent to the cobas b 221 analyzer for assessment of pH for trueness overall and accuracy overall in this externally validated performance evalu-ation in 691 samples.

Identity (x=y) Regression

Blood gasesParameter: pO2 (mmHg)Reference analyzer: cobas b 221 POC systemn = 677, slope = 0.97, r = 1.00, median absolute bias = -3.10 mmHg, accuracy 98 %



10 50 5 3.5 15 9.1

50 140 3.5 5 9.1 10.6

140 700 5 42.7 10.6 99.9

Table 2. Acceptance criteria for pO2 (mmHg) method comparison with blood samples outside the typical range

Parameter: pCO2 (mmHg)Reference analyzer: cobas b 221 POC systemn = 687, slope = 0.95, r = 0.99, median absolute bias = -0.2 mmHg, accuracy 100 %



10 25 4.75 2.5 12.25 5.5

25 70 2.5 2.9 5.5 6.7

70 150 2.9 23.9 6.7 40.9

Table 3. Acceptance criteria for pCO2 (mmHg) method comparison with blood samples outside the typical range

0

20

40

60

80

100

120

0 20 40 60 80 100 120

pCO2 4 Potentiometrycobas b 221 POC system

pCO

2 4

Pot

enti

omet

ryco

bas

b 12

3 PO

C s

yste

m

0

100

200

300

400

500

600

0 100 200 300 400 500 600

pO2 3 Amperometrycobas b 221 POC system

pO2

3 A

mpe

rom

etry

coba

s b

123

POC

sys

tem

-8.0-6.0-4.0-2.00.02.04.06.08.0

Y –

X

pCO2 4 Potentiometrycobas b 221 POC system

0 20 40 60 80 100 120

-80.0-60.0

-100.0

-40.0-20.0

0.020.040.060.080.0

100.0

Y –

X

pO2 3 Amperometrycobas b 221 POC system

0 100 200 300 400 500 600

Key point: The agreement between the cobas b 123 POC system and the cobas b 221 POC system for pO2 was good in the 677 samples assessed in this exter-nally validated performance evaluation, and the accu-racy for pO2 was 98 %.

Key point: The agreement between the cobas b 123 POC system and the cobas b 221 POC system for pCO2 was good, and the accuracy for pCO2 was 100 % in 687 samples assessed in this externally validated performance evaluation.

Figure 3. Trueness overall and accuracy overall: pCO2Figure 2. Trueness overall and accuracy overall: pO2

P/B Regression

Y = 0.9864

X = - 1.8951

md(95) = - 3.100

N = 677 r = 0.9963

t = 0.9587

P/B Regression

Y = 0.953

X = + 1.855

md(95) = 1.36

N = 687 r = 0.9933

t = 0.9162





ElectrolytesParameter: sodium (mmol/L)Reference analyzer: cobas b 221 POC systemn = 691, slope = 1.03, r = 0.94, mean absolute bias = 0.02 %, accuracy 100 %



100 120 5 2.5 11 6.1

120 170 2.5 4.25 6.1 10.25

170 200 4.25 5 10.25 14

Table 4. Acceptance criteria for sodium (mmol/L) method comparison with blood samples outside the typical range

Parameter: potassium (mmol/L)Reference analyzer: cobas b 221 POC systemn = 682, slope = 0.96, r = 0.99, mean absolute bias = -0.03 mmol/L, accuracy 99.9 %



1 3 0.5 0.2 1.1 0.4

3 7 0.2 0.28 0.4 0.63

7 15 0.28 1 0.63 2.6

Table 5. Acceptance criteria for potassium (mmol/L) method comparison with blood samples outside the typical range

100

110

120

130

140

150

160

170

180

190

200

100 110 120 130 140 150 160 170 180 190 200

Na 6 Potentiometrycobas b 221 POC system

Na

6 P

oten

tiom

etry

coba

s b

123

POC

sys

tem

-8.00 %-6.00 %-4.00 %-2.00 %0.00 %2.00 %4.00 %6.00 %8.00 %

100 110 120 130 140 150 160 170 180 190 200

Na 6 Potentiometrycobas b 221 POC system

(Y–X

) /

X [%

]

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

K 7 Potentiometrycobas b 221 POC system

K 7

Pot

enti

omet

ryco

bas

b 12

3 PO

C s

yste

m

-1.00

-0.60

-0.20

0.20

0.60

1.00

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

K 7 Potentiometrycobas b 221 POC system

Y –

X

Figure 4. Trueness overall and accuracy overall: sodium

Key point: Overall, the method comparison of the cobas b 123 POC system vs. cobas b 221 POC system showed comparable results for Na, with 100 % of the values within the 95 percentile.

Figure 5. Trueness overall and accuracy overall: potassium

Key point: Overall, the method comparison of the cobas b 123 POC system vs. cobas b 221 POC system showed a close correlation for K, with 100 % of the values within the 95 percentile.

P/B Regression

Y = 0.956

X = + 0.146

md(95) = - 0.085

N = 682 r = 0.9947

t = 0.9405

Correction factor used!

P/B Regression

Y = 1.034

X = - 4.568

md(95) = 2.365

N = 691 r = 0.9396

t = 0.7600





Parameter: chloride (mmol/L)Reference analyzer: cobas b 221 POC systemn = 657, slope = 1.15, r = 0.98, mean absolute bias = 1.17 %, accuracy 100 %



70 95 4 4 9.14 8.75

95 120 4 4.8 8.75 10.8

120 150 4.8 6 10.8 13.8

Table 6. Acceptance criteria for chloride (mmol/L) method comparison with blood samples outside the typical range

70

80

90

100

110

120

130

140

150

70 80 90 100 110 120 130 140 150

Cl 9 Potentiometrycobas b 221 POC system

Cl 9

Pot

enti

omet

ryco

bas

b 12

3 PO

C s

yste

m

-15.0 %

-10.0 %

-5.0 %

0.0 %

5.0 %

10.0 %

15.0 %

Cl 9 Potentiometrycobas b 221 POC system

70 80 90 100 110 120 130 140 150

(Y–X

) /

X [%

]

Parameter: calcium (mmol/L)Reference analyzer: cobas b 221 POC systemn = 689, slope = 0.95, r = 0.94, mean absolute bias = -0.01 mmol/L, accuracy 100 %



0.1 0.5 0.15 0.1 0.25 0.2

0.5 1.5 0.1 0.09 0.2 0.24

1.5 2.5 0.09 0.25 0.24 0.51

Table 7. Acceptance criteria for calcium (mmol/L) method comparison with blood samples outside the typical range

0.0

0.5

1.0

1.5

2.0

2.5

0.0 0.5 1.0 1.5 2.0 2.5

Ca 8 Potentiometrycobas b 221 POC system

Ca

8 P

oten

tiom

etry

coba

s b

123

POC

sys

tem

-0.300

-0.200

-0.100

0.000

0.100

0.200

0.300

Y –

X

0.0 0.5 1.0 1.5 2.0 2.5

Ca 8 Potentiometrycobas b 221 POC system

Correction factor used!Correction factor used!

Figure 6. Trueness overall and accuracy overall: chloride

Key point: Overall, the method comparison of the cobas b 123 POC system vs. cobas b 221 POC system showed a close correlation for Cl, with 100 % of the values within the 95 percentile.

Figure 7. Trueness overall and accuracy overall: calcium

Key point: Overall, the method comparison of the cobas b 123 POC system vs. cobas b 221 POC system showed comparable results for Ca, with 100 % of the values within the 95 percentile.

P/B Regression

Y = 0.948

X = + 0.048

md(95) = 0.053

N = 689 r = 0.9394

t = 0.7556

P/B Regression

Y = 1.152

X = - 14.913

md(95) = 1.32

N = 657 r = 0.9832

t = 0.8821





Metabolites Parameter: glucose (mmol/L)Reference platform: cobas 6000 analyzer seriesn = 686, slope = 0.98, r = 0.98, median relative bias = -2.4 %, accuracy = 99.7 %



1 4 0.5 0.5 0.8 0.9

4 25 0.5 2.5 0.9 5

25 30 2.5 3.27 5 6.87

Table 8. Acceptance criteria for glucose (mmol/L) method comparison with blood samples outside the typical range

Parameter: lactate (mmol/L)Reference platform: cobas 6000 analyzer seriesn = 590, slope = 1.00, r = 0.99, median relative bias = 0.06 %, accuracy = 100 %



1 2.5 0.5 0.5 0.8 0.8

2.5 12 0.5 1.2 0.8 2.4

12 20 1.2 2.4 2.4 5.2

Table 9. Acceptance criteria for lactate (mmol/L) method comparison with blood samples outside the typical range

0

5

10

15

20

25

0 5 10 15 20 25

GLUC 18 Photometrycobas 6000 analyzer series

GLU

C 1

8 Ph

otom

etry

coba

s b

123

POC

sys

tem

-30.0 %

-20.0 %

-10.0 %

0.0 %

10.0 %

20.0 %

30.0 %

0 5 10 15 20 25

GLUC 18 Photometrycobas 6000 analyzer series

(Y–X

) /

X [%

]

Figure 8. Trueness overall and accuracy overall: glucose

Key point: Overall, there was good correlation between the cobas b 123 POC system and the cobas 6000 analyzer series for glucose in the 686 samples evaluated, with the correlation coefficient for all lots being 0.98 for glucose. The bias of -2.4 % for glucose on the cobas b 123 POC system was within the acceptable range.

Figure 9. Trueness overall and accuracy overall: lactate

Key point: Overall, there was good correlation between the cobas 6000 analyzer series and the cobas b 123 POC system for lactate in the 590 samples evaluated, with the correlation coefficient for all lots being 1.00 for lactate and no samples falling outside the 95 % accuracy limit.

P/B Regression

Y = 0.982

X = - 0.041

md(95) = 0.581

N = 686 r = 0.9794

t = 0.8698

P/B Regression

Y = 1.033

X = - 0.002

md(95) = 0.060

N = 590 r = 0.9816

t = 0.8666



0

2

4

6

8

10

12

14

16

18

20

LAC 3 Photometrycobas 6000 analyzer series

LAC

3 A

mpe

rom

etry

coba

s b

221

POC

sys

tem

0 2 4 6 8 10 12 14 16 18 20-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

Y –

X

0 2 4 6 8 10 12 14 16 18 20

LAC 3 Photometrycobas 6000 analyzer series



HematocritParameter: hematocrit (%)Reference analyzer: cobas b 221 POC systemn = 691, slope 0.95, r = 0.99, mean absolute bias = -0.1 %, accuracy = 99.7 %



10 25 6 3 14 7

25 60 3 3 7 7

60 75 3 6 7 14

Table 10. Acceptance criteria for hematocrit (%) method comparison with blood samples outside the typical range

0

10

20

30

40

50

60

0 10 20 30 40 50 60

Hct 5 Conductivitycobas b 221 POC system

Hct

5 C

ondu

ctiv

ity

coba

s b

123

POC

sys

tem

-10.0

-6.0

-2.0

2.0

6.0

10.0

Y –

X

0 10 20 30 40 50 60

Hct 5 Conductivitycobas b 221 POC system

Total hemoglobinParameter: total hemoglobin (tHb) (g/dL)Reference analyzer: cobas b 221 POC systemn = 682, slope 0.95, r = 0.98, mean absolute bias = 0.3 g/dL, accuracy = 99.3 %



4 10 0.5 0.5 1.2 1.1

10 20 0.5 0.5 1.1 1.1

20 25 0.5 1.2 1.1 2.2

Table 11. Acceptance criteria for total hemoglobin (tHb) (g/dL) method comparison with blood samples outside the typical range

0

2

4

6

8

10

12

14

16

18

20

tHb Coox 10 Spectro-photometricalcobas b 221 POC system

tHb

Coo

x 10

Spe

ctro

-pho

tom

etri

cal

coba

s b

123

POC

sys

tem

0 5 10 15 20-4.0-3.0-2.0-1.00.01.02.03.04.0

Y –

X

0 5 10 15 20

tHb Coox 10 Spectro-photometricalcobas b 221 POC system

Figure 10. Trueness overall and accuracy overall: hematocrit

Key point: The agreement between the cobas b 123 POC system and the cobas b 221 POC system for hematocrit was good, and the accuracy for hematocrit was almost 100 %.

Key point: The agreement between the cobas b 123 POC system and the cobas b 221 POC system for tHb was good, and the accuracy for tHb was 99.3 %, with only few outliers.

Figure 11. Trueness overall and accuracy overall: total hemoglobin (tHb)

P/B Regression

Y = 0.947

X = + 0.252

md(95) = 0.444

N = 682 r = 0.9812

t = 0.8958

P/B Regression

Y = 0.949

X = + 1.62

md(95) = 1.019

N = 691 r = 0.9891

t = 0.9227





Hemoglobin derivates Parameter: COHb (%)Reference analyzer: cobas b 221 POC systemn = 682, slope 1.00, r = 0.97, mean absolute bias = 0.0 %, accuracy = 100 %



0 20 1 3 2 4

20 70 3 7 4 8.4

Table 12. Acceptance criteria for COHb (%) method comparison with blood samples outside the typical range

Parameter: HHb (%)Reference analyzer: cobas b 221 POC systemn = 668, slope 1.01, r = 0.99, mean absolute bias = -0.6 %, accuracy = 98.8 %



0 70 2 2 5 5

Table 13. Acceptance criteria for HHb (%) method comparison with blood samples outside the typical range

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

0.0 2.0 4.0 6.0 8.0 10.0

COHb 13 Spectro-photometricalcobas b 221 POC system

CO

Hb

13 S

pect

ro-p

hoto

met

rica

lco

bas

b 12

3 PO

C s

yste

m

-2.5

-1.5

-0.5

0.5

1.5

2.5

Y –

X

0.0 2.0 4.0 6.0 8.0 10.0

COHb 13 Spectro-photometricalcobas b 221 POC system

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70

HHb 16 Spectro-photometricalcobas b 221 POC system

HH

b 16

Spe

ctro

-pho

tom

etri

cal

coba

s b

123

POC

sys

tem

-10.0

-6.0

-2.0

2.0

6.0

10.0

Y –

X

0 10 20 30 40 50 60 70

HHb 16 Spectro-photometricalcobas b 221 POC system

Figure 12. Trueness overall and accuracy overall: COHb

Key point: The agreement between the cobas b 123 POC system and the cobas b 221 POC system for COHb was excellent.

Figure 13. Trueness overall and accuracy overall: HHb

Key point: The agreement between the cobas b 123 POC system and the cobas b 221 POC system for HHb was excellent, with a slight negative bias due to some outliers.

P/B Regression

Y = 1.014

X = - 0.721

md(95) = 1.401

N = 668 r = 0.9975

t = 0.9083

P/B Regression

Y = 1.0

X = + 0.0

md(95) = 0.212

N = 682 r = 0.9678

t = 0.7687





Parameter: MetHb (%)Reference analyzer: cobas b 221 POC systemn = 682, slope 1.00, r = 0.67, mean absolute bias = 0.1 %, accuracy = 100 %



0 10 1 3 2 4

10 70 3 7 4 11.4

Table 14. Acceptance criteria for MetHb (%) method comparison with blood samples outside the typical range

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

0 1 2 3 4 5 6 7 8 9 10

MetHb 14 Spectro-photometricalcobas b 221 POC system

Met

Hb

14 S

pect

ro-p

hoto

met

rica

lco

bas

b 12

3 PO

C s

yste

m

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

Y –

X

0.0 0.5 1.0 1.5 2.0 2.5 3.0

MetHb 14 Spectro-photometricalcobas b 221 POC system

Parameter: O2Hb (%)Reference analyzer: cobas b 221 POC systemn = 666, slope 1.00, r = 0.99, mean absolute bias = 0.5 %, accuracy = 99.4 %



30 100 3 3 6 6

Table 15. Acceptance criteria for O2Hb (%) method comparison with blood samples outside the typical range

30

40

50

60

70

80

90

100

30 40 50 60 70 80 90 100

O2Hb 12 Spectro-photometricalcobas b 221 POC system

O2H

b 12

Spe

ctro

-pho

tom

etri

cal

coba

s b

123

POC

sys

tem

-10.0

-6.0

-2.0

2.0

6.0

10.0

Y –

X

30 40 50 60 70 80 90 100

O2Hb 12 Spectro-photometricalcobas b 221 POC system

Figure 14. Trueness overall and accuracy overall: MetHb

Key point: The agreement between the cobas b 123 POC system and the cobas b 221 POC system for MetHb was good. The Pearson’s coefficient® is of limited value here.

Figure 15. Trueness overall and accuracy overall: O2Hb

Key point: The agreement between the cobas b 123 POC system and the cobas b 221 POC system for O2Hb was excellent, with good accuracy and very few outliers.

P/B Regression

Y = 1.007

X = - 0.165

md(95) = 1.425

N = 666 r = 0.9973

t = 0.9108

P/B Regression

Y = 1.0

X = + 0.1

md(95) = 0.212

N = 682 r = 0.6665

t = 0.5692





Oxygen saturation Parameter: SO2 (%)Reference analyzer: cobas b 221 POC systemn = 666, slope 1.01, r = 0.99, mean absolute bias = 0.6 %, accuracy = 99.2 %



30 100 2 2 6 6

Table 16. Acceptance criteria for SO2 (%) method comparison with blood samples outside the typical range

Total bilirubin (neonatal)Parameter: total bilirubin (neonatal blood) (mg/dL) Reference analyzer: cobas c 501 module (part of cobas 6000 analyzer series)n = 139, slope 1.206, r = 0.9200, accuracy = 95.7 %, mean overall pooled bias = -0.50, median overall pooled bias = -0.80



3 30 1.2 1.2 3 3

30 50 1.2 5 3 11

Table 17. Acceptance criteria for total bilirubin (neonatal blood) (mg/dL) method comparison with blood samples outside the typical range

30

40

50

60

70

80

90

100

30 40 50 60 70 80 90 100

SO2 11 Specto-photometricalcobas b 221 POC system

SO

2 11

Spe

cto-

phot

omet

rica

lco

bas

b 12

3 PO

C s

yste

m

0

5

10

15

20

25

30

35

40

45

50

0 5 10 15 20 25 30 35 40 45 50

Doumas et al.

Bili

Pho

tom

etry

coba

s b

123

POC

sys

tem

-10.0

-6.0

-2.0

2.0

6.0

10.0

Y –

X

30 40 50 60 70 80 90 100

SO2 11 Specto-photometricalcobas b 221 POC system

-15.0

-10.0

-5.0

5.0

0

10.0

15.0

Y –

X

0 5 10 15 20 25 30 35 40 45 50

Doumas et al.

Figure 16. Trueness overall and accuracy overall: SO2

Key point: The agreement between the cobas b 123 POC system and the cobas b 221 POC system for SO2 was excellent, with good accuracy and very few outliers.

Key point: Generally, there was a good agreement between bilirubin concentrations measured between cobas b 123 POC system and cobas c 501 module (part of cobas 6000 analyzer series). The slope of the regression lines were close to 1, and no significant systematic bias between the two test methods was observed

Figure 17. Trueness overall and accuracy overall: pooled data from three US sites, bilirubin

P/B Regression

Y = 1.015

X = - 0.737

md(95) = 1.485

N = 666 r = 0.9973

t = 0.9075

P/B Regression

Y = 0.9816

X = + 0.2769

md(95) = -0.112

N = 148 r = 0.9855

t = 0.8666





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