Survey Report 2010-4 LA.pdf - NASCOLA

ECAT FOUNDATION EXERCISE 2010-4 

INTERNATIONAL EXTERNAL QUALITY ASSESSMENT Page 1 of 11 

PROGRAMME IN HAEMOSTASIS AND THROMBOSIS Print date: 28 February 2011 

Copyright © 2010 ECAT Foundation 

Labcode: 900 

LUPUS ANTICOAGULANT 

LABORATORY CODE NUMBER: 900 

Test plasma : 10.78 

Type of plasma : Normal pooled plasma enriched with human CRP (127 mg/L) 

Former used in exercise : - 

Number of participants : 436 

Number of responders : 363 

Participation rate : 83% 

General remarks 

1. To make the calculation of ratios possible we entered the maximum measured value into the database when results 

were reported as >[value]. 

2. Seven participants did not gave a final conclusion (!). 

Human plasma with elevated CRP levels 

Recently it was shown that plasma with an elevated CRP level may interfere in Lupus Anticoagulant testing 

(Schouwers et al, Thromb Research; 125 (2010): 102 – 104). Especially an APTT-based test system seems to be 

sensitive to elevated CRP levels. At CRP levels > 53 mg/L the confirmation test showed a Lupus Anticoagulant 

positivity. The dRVVT test used showed no interference with an elevated CRP level. 

Therefore, in this survey we distributed a Lupus Anticoagulant negative pooled plasma which was enriched with CRP to 

a level of 127 mg/L. 

Positive classification 

This lupus negative sample was positively classified by 59 participants (~16%) !!! Twenty-one participants (~6%) 

classified the sample as borderline. 

Screening tests 

Prolonged clotting times were mostly observed in the APTT and dAPTT group (70 and 85% respectively). In the other 

assay groups a prolongation was only rarely found. The table below showed for the most frequently used APTT 

reagents the classification. 

SCREEN Normal (%) Borderline (%) Prolonged (%) 

APTT SP (IL) 53% 11% 36% 

HemosIL SynthASil (IL) 73% 20% 7% 

Pathromtin SL (Siemens) 3% 7% 90% 

Actin FSL (Siemens) 8% 8% 84% 

PTT Automate / STA APTT 

(Stago) 

0% 0% 100% 

PTT LA (Stago) 6% 0% 94% 

It is remarkable that both reagents from I.L. showed less sensitivity to a CRP positive sample than the other frequently 

used reagents.





Labcode: 900 

Mixing tests 

For the mixing tests the APTT and dAPTT showed in 38% and 60% of the cases, respectively, a prolonged test result. 

The table below showed again for the most frequently used APTT reagents the classification. 

MIXING Normal (%) Borderline (%) Prolonged (%) 

APTT SP (IL) 86% 9% 5% 

HemosIL SynthASil (IL) 100% 0% 0% 

Pathromtin SL (Siemens) 61% 38% 11% 

Actin FSL (Siemens) 46% 27% 27% 


(Stago) 

17% 25% 58% 

PTT LA (Stago) 19% 9% 72% 

From this table it is clear that the majority of users of the indicated Stago reagents classified this sample in the mixing 

test borderline or prolonged. For the indicated Siemens reagents an intermediate pattern was observed, while the vast 

majority of the users of the indicated I.L. reagents classified the sample as normal in the mixing test. 

Confirmation test 

A positive confirmation test was almost only observed in the APTT and dAPTT assay groups (46% and 47%, 

respectively). 

The most frequently used APTT-based confirmation test are Siemens Actin FS (n=21) and Stago Staclot LA (n=49). For 

Actin FS 24% classified the test as positive and 14% as borderline. For the Staclot LA test this is 86% (!) and 6%, 

respectively. 

Conclusion 

These findings show that, depending on the method used, a false positive Lupus Anticoagulant test could be observed 

using an APTT based assay system. 

The ISTH criteria indicate that when at least one of the test systems used showed a positive lupus test the sample 

should be identified as Lupus Anticoagulant positive. In the case of a sample with an elevated CRP level this could lead 

to a falsely positive classified sample.





Labcode: 900 

Overview ratio ECAT plasma / normal plasma 

RATIO SCREENING n mean CV Range 

APTT 253 1.43 16.8% 0.69 – 2.12 

APTT SP (IL) 32 1.24 8.1% 1.06 – 1.40 

HemosIL SynthASil (IL) 14 1.16 6.4% 1.06 – 1.33 

Pathromtin SL (Siemens) 24 1.35 8.1% 1.13 – 1.56 

Actin FSL (Siemens) 42 1.39 10.1% 0.99 – 1.74 


(Stago) 

24 1.71 9.9% 1.24 – 2.12 

PTT LA (Stago) 71 1.66 9.0% 1.21 – 1.95 

DRVVT 289 1.02 10.8% 0.79 – 2.10 

DVVtest (AD) 18 0.96 9.6% 0.82 – 1.17 

LAC screen (I.L.) 66 1.07 10.3% 0.91 – 1.59 

LA screen (Life Diagnostics) 26 1.03 8.5% 0.88 – 1.19 

LA check (Precision Biologic) 15 0.96 7.1% 0.79 – 1.08 

LA1 screen (Siemens) 105 1.00 13.0% 0.79 – 2.10 

DRVVT Screen (Stago) 38 0.99 6.1% 0.89 – 1.21 

KCT 22 1.05 26.7% 0.69 – 1.73 

dAPTT 16 1.40 22.1% 0.95 – 2.08 

dPT 24 1.04 10.6% 0.83 – 1.28 

Innovin (Siemens) 11 1.03 9.7% 0.83 – 1.15 

SCT 17 1.11 14.4% 0.80 – 1.48 

Other 2 1.26 - 1.24 – 1.28 

Remarks: 

The high CV of the dAPTT-group and KCT-group in comparison to the other assay groups is 

remarkable. The relatively high CV in the aPTT group in comparison to previous surveys is 

caused by the differences in sensitivity to CRP between the different reagents. Within a particular 

aPTT reagent group the CVs relatively low. 

RATIO MIXING n mean CV range 

APTT 204 1.21 14.0% 0.82 – 2.02 

APTT SP (IL) 22 1.12 7.9% 0.82 – 1.25 

Pathromtin SL (Siemens) 16 1.11 6.2% 0.99 – 1.24 

Actin FSL (Siemens) 36 1.20 6.9% 0.99 – 1.38 


(Stago) 

24 1.34 10.4% 1.15 – 1.75 

PTT LA (Stago) 69 1.32 13.6% 0.92 – 2.02 

DRVVT 100 1.00 8.5% 0.77 – 1.59 

LAC screen (I.L.) 17 1.04 14.4% 0.92 – 1.59 

LA screen (Life Diagnostics) 10 0.98 4.7% 0.90 – 1.05 

LA1 screen (Siemens) 45 0.99 6.3% 0.77 – 1.10 

DRVVT Screen (Stago) 12 1.03 6.5% 0.94 – 1.21 

KCT 19 0.96 12.5% 0.67 – 1.20 

dAPTT 14 1.20 13.3% 0.99 – 1.59 

dPT 12 1.03 7.1% 0.96 – 1.23 

SCT 3 1.02 - 0.99 – 1.06 

Other 1 0.97 - - 

Remarks: 

The relatively high CV in the aPTT group in comparison to other assay groups is caused by the 

differences in sensitivity to CRP between the different reagents. Within a particular aPTT reagent 

group the CV is in most cases relatively low.





Labcode: 900 

RATIO CONFIRMATION n mean CV range 

APTT 54 1.19 12.6% 0.73 – 1.54 

Actin FS (Siemens) 19 1.25 6.6% 1.00 – 1.36 

PT 6 1.00 - 0.94 – 1.08 

DRVVT 212 1.07 9.3% 0.72 – 1.65 

DVV Confirm (AD) 14 1.03 11.7% 0.72 – 1.32 

LAC confirm (I.L.) 55 1.11 9.9% 0.84 – 1.52 

LA confirm (Life Diagnostics) 18 1.05 5.2% 0.95 – 1.16 

LA Sure (Precision Biologic) 8 1.03 - 0.97 – 1.17 

LA2 confirmation (Siemens) 74 1.06 9.4% 0.89 – 1.65 

DRVVT Confirm (Stago) 23 1.05 5.1% 0.91 – 1.15 

KCT 3 1.42 - 0.99 – 2.03 

PNP 4 1.04 - 0.94 – 1.13 

dAPTT 12 1.11 20.7% 0.63 – 1.53 

dPT 8 0.98 - 0.87 – 1.11 

SCT 12 1.37 20.4% 0.70 – 1.70

Count 

Count 

2.2 

2.1 

2.0 

1.9 

1.8 

1.7 

1.6 

1.5 

1.4 

1.3 

1.2 

1.1 

1.0 

.9 

.8 

.7 

.6 

2.2 

2.1 

2.0 

1.9 

1.8 

1.7 

1.6 

1.5 

1.4 

1.3 

1.2 

1.1 

1.0 

.9 

.8 

.7 

.6 

Count 

2.2 

2.1 

2.0 

1.9 

1.8 

1.7 

1.6 

1.5 

1.4 

1.3 

1.2 

1.1 

1.0 

.9 

.8 

.7 

.6 





Labcode: 900 

LUPUS ANTICOAGULANT (Test plasma 10.78) 

200 

assay type 

. 

other 

100 

SCT 

dPT(TTI) 

dAPTT 

KCT 

DRVVT 

0 

APTT 

lupus screening 

APTT 

50 

DRVVT 

200 

40 

methods 

. 

methods 

. 

30 

20 

88.0 

62.0 

57.0 

100 

107.00 

80.00 

31.00 

29.0 

27.00 

10 

21.0 

5.00 

7.0 

1.00 

0 

other 

0 

other 



SCREENING 

normal 

Border 

line 

Prolonged 

your result 

screening 1 screening 2 screening 3 

APTT 73 16 205 

DRVVT 323 9 6 

KCT 21 1 2 

dAPTT 2 1 17 

dPT(TTI) 22 1 2 

SCT 13 2 4 

other 1 0 1 

For 8 screening tests no classification was given.

Count 

2.10 

2.00 

1.90 

1.80 

1.70 

1.60 

1.50 

1.40 

1.30 

1.20 

1.10 

1.00 

.90 

.80 

.70 

.60 





Labcode: 900 


120 

100 

80 

60 

40 

20 

assay type 

. 

other 

SCT 

dPT(TTI) 

dAPTT 

KCT 

DRVVT 

0 

APTT 

lupus mixing 

MIXING 

normal 

Border 

line 

Prolonged 

your result 

mixing 1 mixing 2 mixing 3 

APTT 105 32 83 

DRVVT 105 0 2 

KCT 19 0 1 

dAPTT 4 2 9 

dPT(TTI) 10 0 2 

SCT 3 0 0 

other 1 0 0 

For 7 mixing studies no classification was given.

Count 

2.10 

2.00 

1.90 

1.80 

1.70 

1.60 

1.50 

1.40 

1.30 

1.20 

1.10 

1.00 

.90 

.80 

.70 

.60 

Count 

.60 

.70 

.80 

1.00 

.90 

1.10 

1.20 

1.30 

1.40 

1.50 

1.60 

1.70 

1.80 

1.90 





Labcode: 900 


120 

100 

assay type 

. 

140 

120 

assay type 

. 

80 

60 

SCT 

dPT 

dAPTT 

PNP 

100 

80 

60 

SCT 

dPT 

dAPTT 

PNP 

40 

KCT 

40 

KCT 

20 

DRVVT 

PT 

20 

DRVVT 

PT 

0 

APTT 

0 

APTT 

lupus confirmation 

Ratio Screen/Confirm 

CONFIRMATION 

Positive 

Border- 

Line 

negative 

your result 

confirm 1 confirm 2 confirm 3 

APTT 44 9 42 

PT 0 0 6 

DRVVT 3 3 249 

KCT 1 1 1 

PNP 0 0 4 

dAPTT 14 2 14 

dPT 0 0 8 

SCT 1 0 14 

Other - - - 

RATIO SCREENING/ 

CONFIRMATION 

n Mean CV range your result 

ratio 1 ratio 2 ratio 3 

326 1.01 12.9% 0.62 – 1.76 

FINAL 

CONCLUSION 

negative 

Borderline 

weakly 

positive 

positive 

clearly 

positive 

your result 

276 21 14 41 4





Labcode: 900 

ANTICARDIOLIPIN ANTIBODIES 





Responders Number Percentage 

IgG 161 37% 

IgM 147 34% 

Remarks 

1. About 75 - 80% of the participants reported their results in GPL or MPL units. Only for those category a histogram is 

reported. 

2. Several participants reported a result < [value]. In general the value indicated was included into the statistical 

evaluations with the exception if the value was 5 or higher. 

3. Most of the participants who reported their results in the category “Others” indicated their results in U/mL. 

For most of the methods this seems to be the same as GPL or MPL, because the results in both unit categories are 

comparable. It is highly recommend to report results according to the unit indicated in the kit insert. 

Overview of methods used for anticardiolipin antibody testing 

IgG IgM 

Code Description No. No. 

2003 Aeskulisa Diagnotic GmbH 3 3 

2076 AIDA 1 1 

2009 Biomed 

2005 Bio-rad 2 2 

2007 BMD Cardiolisa 

2008 Cambridge Life Sciences 2 2 

2011 Corgenix Reaads 7 6 

2015 Diagnostica Stago 1 1 

2016 Diamedix 1 1 

2017 DiaSorin Inc. 5 5 

2018 Euro Diagnostica 

2019 Euroimmun 15 15 

2023 Genisis Diagnostics 1 

2027 Hycor Biomedical 

2029 IBL 

2031 Immuno Cocepts RELISA 

2032 Imtec GmbH 4 4 

2033 INOVA Diagnostics Inc. 16 15 

2035 Instrumentation Laboratory 1 1 

2036 IL Acustar 1 1 

2045 Louisville APL Diagnostics 4 3 

2055 Orgentec (Elisa) 28 24 

2056 Orgentec (Alegria) 10 11 

2058 Phadia 28 25 

2060 Pharmacia Diagnostics Varelisa 1 1 

2067 SMC technology 1 

2068 The Binding Site 2 2 

2072 Trinity Biotech 1 1 

2074 Varelisa 9 7 

2075 Vital Diagnostics 4 4 

2090 Homemade 5 4 

2099 Unknown 8 9 

CLASSIFICATION 

Negative Borderline Low positive Medium positive High positive 

No 

conclusion 

IgG 156 0 1 0 0 4 

IgM 146 0 0 0 0 1

Count 

.0 

1.0 

2.0 

3.0 

4.0 

5.0 

6.0 

7.0 

10.0 

11.0 

Count 

.0 

1.0 

2.0 

3.0 

4.0 

5.0 

6.0 

7.0 

9.0 





Labcode: 900 

ANTICARDIOLIPIN ANTIBODIES 

IgG 

IgM 

50 

40 

40 

30 

30 

20 

20 

10 

10 

0 

0 

Anticardiolipin IgG (GPL) 

Anticardiolipin IgM (MPL) 

ANTICARDIOLIPIN (IgG) 

n mean CV range your result 

Unit: GPL 

Total Group 115 2.0 94% 0.0 – 11.2 

Inova 8 3.0 - 0.0 – 5.0 

Orgentec (Elisa) 22 2.1 135% 0.0 – 11.2 

Phadia 25 1.1 72% 0.2 – 4.0 

Unit: µg/mL 

Total Group 2 0.82 - 0.6 – 1.00 

Unit: Other 

Total Group 22 2.0 95% 0.0 – 8.1 

ANTICARDIOLIPIN (IgM) 

N mean CV Range your result 

Unit: MPL 

Total Group 104 1.8 100% 0.0 – 9.0 

Inova 8 4.5 - 0.0 – 6.5 


Phadia 22 0.7 135% 0.0 – 4.0 

Unit: µg/mL 

Total Group 2 0.8 - 0.6 – 1.0 

Unit: Other 

Total Group 22 2.2 132% 0.0 – 12.3 

Remarks: 

None





Labcode: 900 

ß2-GLYCOPROTEIN I ANTIBODIES 





Responders Number Percentage 

IgG 124 28% 

IgM 101 23% 

Remarks 

1. About 70 - 75% if the participants reported their results in U. Only for those category a histogram is reported. 

2. Several participants reported a result < [value]. In general the value indicated was included into the statistical 

evaluations with the exception if the value was 5 or higher. 

3. Most of the participants who reported their results in the category “Others” indicated their results in U/mL. 

For most of the methods this seems to be the same as U, because the results in both unit categories are comparable. It 

is highly recommend to report results according to the unit indicated in the kit insert. 

Overview of methods used for ß2-Glycoprotein I antibody testing 

IgG IgM 

Code Description No. No. 

2003 Aeskulisa Diagnotic GmbH 6 6 

2076 AIDA 1 1 

2009 Biomed 

2005 Bio-rad 3 2 

2011 Corgenix Reaads 7 5 

2017 DiaSorin Inc. 

2018 Euro Diagnostica 1 

2019 Euroimmun 11 9 

2032 Imtec GmbH 7 4 

2033 INOVA Diagnostics Inc. 18 15 

2035 Instrumentation Laboratory 1 1 

2036 IL Acustar 1 1 

2055 Orgentec (Elisa) 20 18 

2056 Orgentec (Alegria) 8 9 

2058 Phadia 25 17 

2060 Pharmacia Diagnostics Varelisa 1 1 

2067 SMC Technology 1 

2068 The Binding Site 2 1 

2072 Trinity Biotech 1 1 

2074 Varelisa 2 1 

2090 Homemade 2 2 

2099 Unknown 7 6 

CLASSIFICATION 

Negative Borderline Low positive Medium positive High positive 

No 

conclusion 

IgG 120 0 0 0 0 4 

IgM 98 1 0 0 0 2

Count 

.0 

1.0 

2.0 

3.0 

4.0 

5.0 

6.0 

7.0 

9.0 

Count 

.0 

1.0 

2.0 

3.0 

4.0 

5.0 

6.0 

> 11.5 

9.0 





Labcode: 900 

ß2-GLYCOPROTEIN I ANTIBODIES 

IgG 

IgM 

40 

30 

30 

20 

20 

10 

10 

0 

0 

ß2-Glycoprotein I IgG (U) 

ß2-Glycoprotein I IgM (U) 

ß2-GLYCOPROTEIN I (IgG) 


Unit: U 

Total Group 84 1.8 102% 0.0 – 9.2 

Inova 10 3.1 92% 0.0 – 9.2 


Phadia 19 0.7 96% 0.0 – 3.0 

Unit: µg/mL 

Total Group 4 2.5 - 0.1 – 5.0 

Unit: Other 

Total Group 25 2.0 100% 0.0 – 7.0 

RATIO 11 0.28 139% 0.03 – 1.20 

ß2-GLYCOPROTEIN I (IgM) 


Unit: U 

Total Group 70 2.2 171% 0.0 – 16.5 

Inova 9 1.2 - 0.0 – 4.1 


Phadia 15 0.4 88% 0.0 – 1.0 

Unit: µg/mL 

Total Group 4 0.5 - 0.1 – 1.0 

Unit: Other 

Total Group 21 1.4 96% 0.0 – 4.9 

RATIO 9 0.26 - 0.05 – 1.10 

Remarks: 

None

Survey Report 2010-4 LA.pdf - NASCOLA

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