EXPERT COMMITTEE ON BIOLOGICAL STANDARDIZATION...3264; fax: +41 22 791 4857; e-mail:...

WHO/BS/2016.2294

ENGLISH ONLY

EXPERT COMMITTEE ON BIOLOGICAL STANDARDIZATION

Geneva, 17 to 21 October 2016

Calibration of the Proposed 5th

International Standard for Thromboplastin,

human, recombinant, plain (rTF/16; study code 14/001) and the Proposed 5th

International Standard for Thromboplastin, rabbit, plain (RBT/16; study

code 15/001)

Antonius M.H.P. van den Besselaar1, Veena Chantarangkul

2 and Armando Tripodi

2

1Department of Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, The

Netherlands 2Angelo Bianchi Bonomi Hemophilia and Thrombosis Centre, Department of Clinical Sciences

and Community Health, Università degli Studi di Milano and IRCCS Cà Granda Maggiore

Hospital Foundation, Milano, Italy

NOTE:

This document has been prepared for the purpose of inviting comments and suggestions on the

proposals contained therein, which will then be considered by the Expert Committee on

Biological Standardization (ECBS). Comments MUST be received by 16 September 2016 and

should be addressed to the World Health Organization, 1211 Geneva 27, Switzerland, attention:

Technologies, Standards and Norms (TSN). Comments may also be submitted electronically to

the Responsible Officer: Dr C M Nübling at email: [email protected].

© World Health Organization 2016

All rights reserved. Publications of the World Health Organization are available on the WHO web site (www.who.int) or can be

purchased from WHO Press, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland (tel.: +41 22 791

3264; fax: +41 22 791 4857; e-mail: [email protected]).

Requests for permission to reproduce or translate WHO publications – whether for sale or for noncommercial distribution –

should be addressed to WHO Press through the WHO web site:

(http://www.who.int/about/licensing/copyright_form/en/index.html).

The designations employed and the presentation of the material in this publication do not imply the expression of any opinion

whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its

authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines

for which there may not yet be full agreement.

The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended

http://www.who.int/

mailto:[email protected]

http://www.who.int/about/licensing/copyright_form/en/index.html

WHO/BS/2016.2294

2

by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omissions

excepted, the names of proprietary products are distinguished by initial capital letters.

All reasonable precautions have been taken by the World Health Organization to verify the information contained in this

publication. However, the published material is being distributed without warranty of any kind, either expressed or implied. The

responsibility for the interpretation and use of the material lies with the reader. In no event shall the World Health Organization

be liable for damages arising from its use. The named authors alone are responsible for the views expressed in this publication.

Summary

Background and aim:

Stocks of the current 4th

International Standard for Thromboplastin, human, recombinant, plain

(coded rTF/09) and the current 4th

International Standard for Thromboplastin, rabbit, plain

(coded RBT/05) are running low. Candidate replacement materials have been prepared

(provisionally coded 14/001 and 15/001, respectively). This report describes the calibration of

the proposed 5th

International Standard for Thromboplastin, human, recombinant, plain, and the

proposed 5th

International Standard for Thromboplastin, rabbit, plain.

Methods

An international collaborative study was carried out for the assignment of International

Sensitivity Index (ISI) to the candidate materials. Results were obtained from 20 laboratories.

The validity of each and every ISI assessment was checked using criteria published by the WHO

Expert Committee on Biological Standardization. Only valid ISI assessments were used to

calculate the mean ISI for each candidate.

Results

The mean ISI for candidate 14/001 was 1.11 (between-laboratory CV: 5.7%) and the mean ISI

for candidate 15/001 was 1.21 (between-laboratory CV: 4.6%).

Accelerated degradation tests were performed to assess the stability of the freeze-dried candidate

materials. There was no significant change of the prothrombin time after storage of the candidate

materials at 5°C for 56 days. After storage at elevated temperatures (31°C - 42°C) there was a

slight but significant change of the prothrombin time. The stability after reconstitution was

assessed at room temperature, over a time interval of 0.5 - 4 hours. Between 1 and 4 hours after

reconstitution, there was no change of the prothrombin time with candidate 14/001, and a slight

change (-1.5%) with candidate 15/001.

Conclusion and proposal

It is proposed that candidate 14/001 is accepted as the WHO 5th

International Standard for

Thromboplastin, human, recombinant, plain, and candidate 15/001 as the WHO 5th

International

Standard for Thromboplastin, rabbit, plain. Upon establishment, it is proposed to replace the

provisional coding of the candidates by rTF/16 and RBT/16, respectively.

WHO/BS/2016.2294

Introduction

Treatment with vitamin K-antagonists (VKA) must be monitored to adjust the dose if necessary.

The primary laboratory method for monitoring of VKA is the prothrombin time test (PT). The

PT test is performed with a thromboplastin reagent and a method or instrument to determine the

coagulation time in seconds. Various types of thromboplastin are prepared commercially and, in

order to be able to interpret the results of the PT test, it is essential that each reagent is correctly

calibrated (1). This will ensure that the results of tests with different products and batches can be

compared. A procedure for the calibration of thromboplastins using a logarithmic plot of PTs has

been developed. With this procedure, the definition of a calibration parameter called

International Sensitivity Index (ISI) became feasible. It is possible to express PT results on a

common scale, i.e. the International Normalized Ratio (INR), if the ISI of the thromboplastin

used is known.

Two International Standards for thromboplastin are presently available for calibration of

secondary standards or commercial thromboplastin preparations: the Fourth International

Standard for thromboplastin, rabbit, plain (coded RBT/05) and the Fourth International Standard

for thromboplastin, human, recombinant (coded rTF/09)(2, 3). In general, the calibration of a

given thromboplastin reagent is more precise if performed against an International Standard of

similar composition and from the same species. Thus, plain rabbit thromboplastins should be

calibrated against RBT/05 and plain human thromboplastins against the human recombinant

material rTF/09.

Stocks of both rTF/09 and RBT/05 are now running low and replacements are required.

Candidate replacement materials have been prepared for thromboplastin, human, recombinant,

plain (provisionally coded 14/001) and for thromboplastin, rabbit, plain (provisionally coded

15/001). The calibration of the candidate replacement materials should be carried out as part of

international multicentre collaborative studies using fresh coumarin and fresh normal plasmas

and using manual techniques for PT determination. The ISI assigned to each replacement

material should be the mean of the ISIs obtained by calibration with both existing International

Standards, i.e. rTF/09 and RBT/05. The present report deals with the results of an international

collaborative study organized under the auspices of the Scientific and Standardization

Committee (SSC) of the International Society on Thrombosis and Haemostasis (ISTH) for the

calibration of the two candidate replacement materials.

WHO/BS/2016.2294

4

Details of Candidate Preparations

Detail Proposed 5th IS Human,

Recombinant, Plain (14/001)

Proposed 5th IS Rabbit Plain

(15/001)

Presentation

Two components sealed in glass

Hodes-Lange type ampoules under

two purified nitrogen flushes:

Dried Thromboplastin (14/001) and

Reconstitution Fluid (14/002)

Two components sealed in glass

Hodes-Lange type ampoules under

two purified nitrogen flushes:

Dried Thromboplastin (15/001) and

Reconstitution Fluid (15/002)

Excipients/additives

Dried Thromboplastin:

Recombinant human tissue factor,

phospholipid mixture with Tris

buffer, sodium chloride, trehalose,

bovine gamma globulin, and

antimicrobials pH 7.4. Manufactured

27 Jan-01 April 2014.

Reconstitution Fluid: calcium

chloride, polybrene and

antimicrobials. Manufactured 07-08

April 2014.

Dried Thromboplastin:

Rabbit brain thromboplastin powder

with Hepes-sodium buffer,

polybrene, glycine, pH 7.3.

Manufactured 05-06 March, 2015.

Reconstitution Fluid: calcium

chloride with Hepes-sodium buffer,

glycine, polybrene, sodium chloride,

PEG 4000 and antimicrobials, pH

7.1. Manufactured 17-18 March,

2015.

Liquid filling weight (g)

Thromboplastin Fill Mean:

0.261g (weight range 0.243-0.273g),

target = 0.265g (target range±10% of

target =0.238-0.292)

Reconstitution Fluid Fill:

Mean >1.6 mL (exceeds 1.0 mL

required)

Thromboplastin Fill Mean:

0.479g (weight range 0.468-0.493g),

target = 0.481g (target range±7.5%

of target =0.445-0.517)

Reconstitution Fluid Fill:

Mean >1.6 mL (exceeds 1.0 mL

required)

Coefficient of variation

of the fill weight (%)

Dried Thrombopalstin CV = 1.9%

based on 117 weight checks per 17

trays/>22000 ampoules

Reconstitution Fluid CV = not

applicable, filled in excess

Dried Thromboplastin CV = 1.2%

based on 52 weight checks per 12

trays/>16700 ampoules

Reconstitution Fluid CV = not

applicable, filled in excess

Coeff. Of Variation of

Thromboplastin PT

across fill (% of

Normal Control)

Mean 9.95 sec (n=18, 17 trays)

CV 1.2% (Spec<4%)

Mean 13.57 sec (n=24, 12 trays)

CV 1.1% (Spec<2%)

Residual moisture after

lyophilisation (%)

Moisture in Dried Thromboplastin by

Laser Absorption (17 samples across

17 trays, 5 measurements per

sample):

Mean p(H2O) = 3.3 torr (range 2.9-

4.6 torr, Target <5.6 torr)

Mean %(w/w) Moisture

(approximate, estimated by KF

correlation) = 3.5%

Moisture in Dried Thromboplastin by

Laser Absorption (12 samples across

12 trays, 3 measurements per

sample):

Mean p(H2O) = 1.8 torr (range 1.2-

2.3 torr, Target <2.51 torr)

Mean %(w/w) Moisture

(approximate, estimated by KF

correlation) = 0.72%

WHO/BS/2016.2294

Headspace oxygen (%)

Mean 0.2 %atm (range 0.1-0.4 %

atm)

Mean 0.4 %atm (Range 0.1-1.3%

atm)

Reconstitution

Procedure

Deliver 1.0 ml of rTF/16

Reconstitution Fluid per one (1)

Dried rTF/16 Thromboplastin

ampoule with swirling, allow 20

minutes at Room Temperature (~15-

25oC) to make 1.0 mL Working

rTF/16 Thromboplastin

Deliver 1.0 ml of RBT/16

Reconstitution Fluid per one (1)

Dried RBT/16 Thromboplastin

ampoule with swirling, allow 30

minutes at Room Temperature (~15-

25oC) to make 1.0 mL Working

RBT/16 Thromboplastin

Number of ampoules in

stock

10,000

10,000

Manufacturing site

Instrumentation Laboratory,

Orangeburg NY, USA

Instrumentation Laboratory,

Orangeburg NY, USA

Custodian

NIBSC, Potters Bar, UK

NIBSC, Potters Bar, UK

Storage temperature

-20 °C (Thromboplastin)

2-8 °C (Reconstitution Fluid)

-20 °C (Thromboplastin)

2-8 °C (Reconstitution Fluid)

Design of the collaborative study for ISI value assignment

Twenty laboratories from Europe, North America, South America, Asia and Australia were

invited to participate in the collaborative study. Fourteen of these had participated in the previous

collaborative study for the calibration of rTF/09 (3). The candidate materials (14/001 and

15/001) and the current International Standards (rTF/09 and RBT/05) were tested in each

laboratory by the same operator with the manual (tilt tube) technique, according to a study

protocol with detailed instructions. Test plasmas were freshly prepared from healthy (“normal”)

subjects and patients on long-term therapy with VKA. Participants were instructed to select

patient plasmas with PT corresponding to an INR interval from 1.5 to 4.5. In addition to the fresh

plasmas, four lyophilized control plasmas were included. To account for the effect of inter-day

variation, PT measurements were performed in each laboratory on 10 different days. Participants

were instructed to include on each day plasmas from two healthy individuals and six patients

treated with VKA. Healthy individuals and patients had to be different on each working day. To

minimize the effect of preanalytical plasma instability on the relationship between

thromboplastins, the order of testing was changed each day. The order of testing was specified in

the data-collection form. The collaborative study was carried out from October 2015 until

February 2016.

Statistical methods

Calculation of ISI for candidate materials The statistical methods have been described in the Guidelines for thromboplastins and plasma

used to control oral anticoagulant therapy with vitamin K antagonists (1). The sequence of steps

in the statistical evaluation for each participant’s calibration is as follows.

WHO/BS/2016.2294

6

1. Calculate preliminary orthogonal regression line (20 normal samples + 60 patient

samples).

2. Detect outliers defined as points with a perpendicular distance greater than 3 residual

standard deviations from the preliminary line.

3. Remove outliers in one step and recalculate the orthogonal regression line (normal

samples + patient samples) and ISI as the product of the slope of the regression line and

the ISI of the International Standard.

4. Calculate each patient’s INR using the PT determined with the International Standard.

5. Calculate each patient’s INR using the PT determined with the candidate material and ISI

from step 3.

6. Calculate each patient’s mean INR from steps 4 and 5.

7. Remove patients with mean INR < 1.5 or mean INR > 4.5.

8. Recalculate the orthogonal regression line for the remaining normal samples + patient

samples and ISI as the product of the slope of the regression line and the ISI of the

International Standard.

Mean ISI and between-laboratory coefficient of variation The arithmetic mean and between-laboratory standard deviation (SD) of ISI assessments was

calculated. The between-laboratory coefficient of variation was calculated as the SD divided by

the mean ISI and multiplied by 100.

Validity of ISI Each and every ISI assessment was checked for validity. The within-laboratory coefficient of

variation (CV) of the slope of the orthogonal regression line for normal samples + patient

samples should be 3% or less (1). ISI assessments with a within-laboratory CV of the slope

larger than 3% were rejected. Secondly, the adequacy of the ISI model was checked. While there

is good evidence that the calibration relationship defined in a double-logarithmic plot of PTs is

usually linear, and that the same line represents data points for both patients and healthy subjects,

the possibility of departure from these assumptions cannot be ruled out. To assess the magnitude

of INR deviations, the orthogonal regression line was calculated for patients’ samples only: Y =

a’ + b’·X, in which Y is the natural logarithm of patient’s PT determined with the International

Standard and X is the natural logarithm of patient’s PT determined with the candidate material.

INRs calculated with the patients’ only line were compared to INRs calculated with the ISI. In

case of marked INR deviation, the assignment of an ISI would not be meaningful. For practical

purposes, the assignment of an ISI is acceptable if INRs calculated with the ISI do not differ by

more than 10%, in the INR range 2 – 4.5, from INRs calculated with the equation describing the

above-mentioned regression line for patients’ samples only (1). Conversely, the assignment of an

ISI is not acceptable if INRs differ by more than 10%. ISI assessments resulting in INR

deviations larger than 10% were rejected.

WHO/BS/2016.2294

Results of ISI value assignment

Geometric mean normal PT (MNPT) and mean patients’ PT are shown in Table 1. The Pearson

correlation between the four different thromboplastins was significant (P<0.001), suggesting that

the mean PT differences between the laboratories were significant.

ISI values calculated including all data are shown in Table 2. The between-laboratory variation

(CV) of like-to-like calibrations (i.e. 2.2% and 4.3% for 14/001 and 15/001 respectively) was

smaller than the CVs for the cross-species calibrations (i.e. 6.4% and 5.6% for 14/001 and

15/001 respectively). The number of outliers (> 3 SD) and samples with INR<1.5 or INR>4.5 is

shown in Table 3. ISI values calculated after exclusion of outliers (>3 SD) are shown in Table 4.

ISI values calculated after exclusion of outliers (> 3 SD) and samples with INR<1.5 or INR>4.5

are shown in Tables 5 and 6. In the cross-species calibration of candidate 15/001 against rTF/09,

there was one laboratory with a CV of the slope (CVB) larger than 3.0% (Table 5). In the

calibration of candidates 14/001 and 15/001 with RBT/05, there were two results with a CV of

the slope (CVB) larger than 3.0% (Table 6).

Intercept (a’) and slope (b’) of the orthogonal regression lines for patients’ samples only are

shown in Table 7. The deviations of the INR calculated with the ISI for the “true INR”=2 and the

“true INR” = 4.5 are shown in Table 8. For the like-to-like calibration of candidate 14/001

against rTF/09, all laboratories had deviations <10%. For the cross-species calibration of

candidate 14/001 against RBT/05, 6 laboratories had deviations larger than 10%. For the like-to-

like calibration of candidate 15/001 against RBT/05, only one laboratory had a deviation larger

than 10%. For the cross-species calibration of candidate 15/001 against rTF/09, 8 laboratories

had deviations larger than 10%.

Table 9 shows the mean ISI and inter-laboratory CV for the candidates before and after

exclusion of non-valid ISI assessments. For candidate 14/001, exclusion of non-valid assessment

had no important effect on the mean ISI. The final mean ISI for candidate 14/001 is 1.11 with a

CV of 5.7%. For candidate 15/001, exclusion of non-valid assessments resulted in a 1% higher

mean ISI and a reduction of the between-laboratory variation of the ISI. The final mean ISI for

candidate 15/001 is 1.21 with a CV of 4.6%.

For each of the lyophilized control plasmas and for each participant, INR was calculated with the

local MNPT and the mean ISI for each Thromboplastin reagent. Table 10 shows the mean INR

and the inter-laboratory SD. The differences between the mean values with the 4 thromboplastin

reagents were relatively small. Further analysis of the INR values for the lyophilized control

plasmas will be performed later.

Stability of the proposed International Standards.

Accelerated degradation study

Tissue factor is a glycoprotein that needs the association with phospholipids for full expression

of its procoagulant activity. Lyophilized tissue factor preparations (thromboplastin) for PT

determination usually contain many other components such as residual water which may

influence the stability of the reagent. In general, the long-term stability of lyophilized tissue

WHO/BS/2016.2294

8

factor from human or animal brain stored at low temperature is excellent. The stability of

lyophilized biological materials may be predicted from accelerated degradation tests. The

purpose of an accelerated degradation test is to measure the relative rates of potency loss at

several temperatures and to extrapolate the rate to the desired temperature of storage. For the

deterioration of lyophilized tissue factor preparations complex kinetics are expected because

tissue factor is a lipoprotein. It may be difficult to predict the stability of tissue factor at low

temperature from the results of an accelerated degradation test. Nevertheless, the results of an

accelerated degradation test may be useful to assess the relative stability under transportation

conditions at various temperatures. The accelerated degradation test is a standard procedure to

check the stability of lyophilized thromboplastin preparations (1).

Following shipment of both candidates (coded 14/001 and 15/001) to Leiden, they were stored at

minus 20°C. The respective reconstitution fluids (coded 14/002 and 15/002) were stored at +5°C.

For the accelerated degradation test, a number of ampoules of 14/001 and 15/001 were stored at

+5°C, +31°C, +36°C, and +42°C, for different time intervals. The time intervals ranged from 1

to 59 days. In fact, the ampoules were placed in the incubators on different dates, so that they all

could be analysed in the same session at the end of the different incubation time intervals. After

storage of the candidates at these temperatures, they were reconstituted and tested with two deep-

frozen pooled plasmas (one normal, coded NP141202, and one coumarin plasma obtained from

patients treated with VKA , coded AP141204). The tests were performed with a semi-automatic,

electro-mechanical coagulometer according to Schnitger and Gross manufactured by Amelung

GmbH (Lemgo, Germany). All ampoules stored at a given temperature were tested in the same

session. In addition, ampoules stored at -20°C were tested in each session. The results obtained

with the ampoules stored at -20°C were considered as the initial value at zero storage time,

assuming that deterioration at -20°C was negligible. The time between reconstitution and of each

ampoule and testing was 2 hours. For each storage temperature and time, 3 ampoules were used.

Each ampoule was tested in single PT determination. The mean values of the 3 PT’s were used

for statistical analysis. For each storage temperature and time, a clotting time ratio (PT ratio) was

calculated as the mean PT of the coumarin plasma divided by the mean PT of the normal plasma

(AP/NP). Correlation coefficients according to Spearman were used to test the change of PT or

PT-ratio with incubation time. A significance level of 5% was used.

PT’s and PT-ratios as a function of storage time at various temperatures are shown in Tables 11

and 12. For candidate 14/001, a slight decrease of the PT of normal and coumarin plasmas at

+36°C and +42°C was observed (Table 11). There was no significant change of PT after storage

at +5°C. A decrease of PT-ratio was observed for candidate 14/001 after storage at +31°C,

+36°C, and +42°C. No significant change of PT-ratio was observed after storage at +5°C (Table

11). For candidate 15/001, a slight increase was observed of the PT of normal and coumarin

plasmas stored at +31°C, +36°C, and +42°C (Table 12). There was no significant change of PT

and PT-ratio after storage at +5°C. The change of PT-ratio at +36°C was significant (Table 12).

In conclusion, the PT-ratio and hence the ISI of both candidates may change after storage at

+31°C, +36°C and +42°C. In contrast, no significant change was observed after storage at +5°C

for 56 days, demonstrating that both candidates are stable during shipment at +5°C. For shipment

at ambient temperature, however, certain precautions may be advised. The shipment duration

WHO/BS/2016.2294

should be limited to a few days. Cooling packs may be included in the parcel to avoid deleterious

effects of elevated temperature.

Stability after reconstitution

To assess the stability of the candidates after reconstitution, they were reconstituted with their

respective reconstitution fluids and kept at room temperature (+22 ± 1°C) for various time

intervals and tested in a PT test. The time intervals were 4, 3, 2, 1, and 0.5 hours, respectively.

For each time interval, three ampoules of each candidate were used. Two deep frozen pooled

plasmas (one normal, coded NP141202, and one coumarin plasma obtained from patients treated

with VKA, coded AP141204) were used for the PT tests. The tests were performed in duplicate

with a semi-automatic, electro-mechanical coagulometer according to Schnitger and Gross

manufactured by Amelung GmbH (Lemgo, Germany). Correlation coefficients according to

Spearman were used to test the change of PT with incubation time. A significance level of 5%

was used.

Mean PT’s as a function of time interval between reconstitution and testing are shown in Tables

13 and 14. There was no change of the mean PT and PT ratio for candidate 14/001 (Table 13).

There was a slight decrease of the mean PT and PT ratio for candidate 15/001 in the first 3 hours

after reconstitution (Table 14). The decrease of PT between 0.5 and 1 hour was greater than that

in the following time intervals (Table 14). It is recommended to use the reagent between 0.5 and

4 hours after reconstitution if it is stored at room temperature.

Conclusion

Upon establishment of the proposed candidate preparations, it is proposed to replace the

provisional codes 14/001 and 15/001 by rTF/16 and RBT/16 respectively. This will facilitate the

recognition and continuity of terminology for international standards for thromboplastins.

References

1. WHO Expert Committee on Biological Standardization. Guidelines for thromboplastins

and plasma used to control oral anticoagulant therapy with vitamin K antagonists. WHO

Technical Report Series 2013; No. 979; pp 271-316.

2. Chantarangkul V, van den Besselaar AMHP, Witteveen E, Tripodi A. International

collaborative study for the calibration of a proposed international standard for

thromboplastin, rabbit, plain. J Thromb Haemost 2006;4:1339-45.

3. Tripodi A, Chantarangkul V, van den Besselaar AMHP, Witteveen E. International

collaborative study for the calibration of a proposed international standard for

thromboplastin, human, plain. J Thromb Haemost 2010;8:2066-8.

WHO/BS/2016.2294

10

Acknowledgements

We wish to thank all participants (see Appendix) of the international collaborative study for their

contribution and the ISTH/SSC Subcommittee on Control of Anticoagulation for their support.

We further acknowledge the following contributions:

Provision of candidates: Instrumentation Laboratory (Orangeburg, NY);

Provision of International Standards: National Institute for Biological Standards and Control

(Potters Bar, United Kingdom);

Provision of control plasmas: Technoclone Herstellung von Diagnostika und Arzneimitteln

GmbH (Vienna, Austria);

Additional support: Stichting Kwaliteitsbewaking Medische Laboratoriumdiagnostiek

(Nijmegen, The Netherlands).

Appendix: List of participants of collaborative calibration study

1. F. Angeloni (Hemostasis Reference Laboratory, Hamilton, Canada)

2. N.B. Binder (Technoclone GmbH, Vienna, Austria)

3. M. Byrne (St James’s Hospital, Dublin, Ireland)

4. V. Chantarangkul and A. Tripodi (University of Milano, Milano, Italy)

5. R. Dauer (Alfred Health, Melbourne, Australia)

6. B.R. Gudmundsdóttir (Landspitali University Hospital, Reykjavik, Iceland)

7. K. Gustafsson and T. Lindahl (Universitetssjukhuset, Linköping, Sweden)

8. J. Jespersen and K. Overgaard (Hospital of South West Denmark, Esbjerg, Denmark)

9. S. Kitchen (Royal Hallamshire Hospital, Sheffield, United Kingdom)

10. C. Legnani and M. Cini (University Hospital S. Orsola-Malpighi, Bologna, Italy)

11. R.A. Manning (Hammersmith Hospital, East Acton, London, United Kingdom)

12. M. Martinuzzo (Laboratorio Central del Hospital Italiano, Buenos Aires, Argentina)

13. O. Panes and D. Mezzano (Escuela de Medicina, Univ. Católica de Chile, Santiago,

Chile)

14. V. Pengo and E. Bison (Laboratorio Trombosi – Clinica Cardiologica, Padova, Italy)

15. A. Riddell and A. Drebes (Royal Free Hospital, London, United Kingdom)

16. S. Subramanian (St John’s Medical College Hospital, Bangalore, India)

17. A. Szederjesi (St Laszlo Hospital – Campus, Budapest, Hungary)

18. C. Tantanate (Siriraj Hospital, Mahidol University, Bangkok, Thailand)

19. A.M.H.P. Van den Besselaar (Leiden University Medical Center, Leiden, The

Netherlands)

20. R. Zerback and P. Herbel (Roche Diagnostics GmbH, Mannheim, Germany)

WHO/BS/2016.2294

TABLE 1

Mean normal prothrombin time (MNPT) and mean VKA patients’ prothrombin time (s).

Mean values were obtained after excluding outliers (>±3SD) and INR<1.5 and INR>4.5.

MNPT Mean VKA patients’ PT

Lab rTF/09 RBT/05 Candidate

14/001

Candidate

15/001

rTF/09 RBT/05 Candidate

14/001

Candidate

15/001

1 14.266 18.064 14.127 19.790 35.428 43.310 34.940 44.095

2 14.205 16.851 14.102 19.193 36.650 45.001 34.072 51.604

3 14.539 16.699 13.940 18.474 34.573 40.893 34.447 44.007

4 11.253 14.367 11.105 14.709 29.292 35.156 28.528 33.800

5 13.199 15.503 12.719 17.090 28.753 35.125 28.014 37.411

6 13.384 15.845 13.290 16.976 31.391 37.415 30.547 40.890

7 12.295 16.328 12.262 17.634 25.935 33.220 25.176 36.500

8 12.101 15.083 11.684 16.535 27.189 35.143 25.426 37.322

9 13.317 16.380 12.703 17.864 30.526 37.060 28.791 38.054

10 13.768 17.738 13.654 18.299 30.789 40.854 29.424 41.340

11 13.159 15.970 12.681 16.976 35.081 38.837 33.285 39.703

12 14.065 16.997 13.547 18.492 32.494 37.584 31.565 39.427

13 13.766 17.722 13.069 18.187 33.357 42.687 31.690 40.794

14 15.490 17.447 14.947 20.294 35.392 40.437 33.802 44.104

15 14.417 17.669 14.188 20.803 38.084 47.223 37.849 48.498

16 12.931 15.938 12.339 16.301 29.776 38.671 28.445 37.271

17 14.236 16.127 14.001 17.913 36.506 39.905 35.303 43.229

18 14.355 16.781 13.803 19.421 36.050 41.255 34.877 46.278

19 15.808 18.734 14.779 20.734 34.470 43.951 32.149 46.402

20 15.262 21.197 15.009 20.877 34.353 43.523 32.975 44.190

Mean 13.79 16.87 13.40 18.33 32.80 39.86 31.57 41.75

Min 11.25 14.37 11.11 14.71 25.93 33.22 25.18 33.80

Max 15.81 21.20 15.01 20.88 38.08 47.22 37.85 51.60

WHO/BS/2016.2294

12

TABLE 2

ISI for Candidates 14/001 and 15/001 including all data. N is the number of normal and

patients’ samples. CV(b) is the coefficient of variation of the orthogonal regression line

slope.

Lab Reference: rTF/09 Reference: RBT/05

Candidate 14/001 Candidate 15/001 Candidate 14/001 Candidate 15/001

N ISI CV(b) N ISI CV(b) N ISI CV(b) N ISI CV(b)

1 80 1.108 2.4 80 1.266 2.7 80 1.078 2.6 80 1.231 1.7

2 80 1.132 1.3 80 1.079 2.1 80 1.289 2.7 80 1.226 2.1

3 80 1.052 2.2 80 1.149 2.9 80 1.094 2.3 80 1.194 1.9

4 80 1.091 1.7 80 1.262 2.6 80 1.046 2.6 80 1.210 2.1

5 80 1.068 1.7 80 1.179 3.0 80 1.096 2.8 80 1.210 2.2

6 80 1.093 2.0 80 1.082 2.4 80 1.152 2.5 80 1.140 1.9

7 80 1.123 1.8 80 1.154 2.5 80 1.124 3.9 80 1.155 3.2

8 80 1.122 0.7 80 1.140 2.2 80 1.206 2.2 80 1.222 1.0

9 80 1.087 1.0 80 1.203 2.0 80 1.117 1.8 80 1.235 1.2

10 79 1.131 2.0 79 1.129 2.9 79 1.188 2.8 79 1.184 1.5

11 80 1.096 1.5 80 1.236 2.9 80 1.053 2.4 80 1.184 1.6

12 80 1.070 1.0 80 1.229 1.7 80 1.043 1.6 80 1.198 1.2

13 80 1.077 1.6 80 1.304 3.2 80 1.039 2.7 80 1.253 1.6

14 80 1.093 1.4 80 1.201 2.2 80 1.139 2.1 80 1.249 1.4

15 80 1.069 0.8 80 1.259 1.2 80 1.126 1.2 80 1.326 0.9

16 80 1.094 2.1 80 1.174 2.7 80 1.155 3.0 80 1.237 1.6

17 80 1.105 1.9 80 1.194 3.0 80 1.080 2.1 80 1.165 2.2

18 80 1.073 1.3 80 1.165 2.1 80 1.115 2.0 80 1.210 1.9

19 80 1.063 2.2 80 1.064 2.8 80 1.211 2.5 80 1.213 2.2

20 88 1.120 1.6 86 1.224 4.0 89 0.988 2.8 87 1.065 3.3

Mean 1.093 1.185 1.117 1.205

CV(interlab) 2.2 5.6 6.4 4.3

WHO/BS/2016.2294

TABLE 3

Number of outliers > ±3SD and INR<1.5 and INR>4.5



>±3SD <1.5 >4.5 >±3SD <1.5 >4.5 >±3SD <1.5 >4.5 >±3SD <1.5 >4.5

1 1 1 1 1 1 1 0 1 2 2 0 1

2 1 0 1 0 0 9 1 0 1 0 0 6

3 0 1 0 0 1 0 0 1 0 0 0 0

4 0 0 1 1 0 0 0 0 2 1 0 0

5 0 1 1 1 0 0 0 0 0 1 0 0

6 0 0 0 0 0 0 0 0 0 2 0 0

7 0 3 2 0 2 2 0 1 2 0 0 2

8 0 0 0 1 0 1 1 0 0 1 0 0

9 0 3 0 0 1 0 0 1 0 1 0 0

10 1 0 0 0 0 0 0 0 0 0 0 0

11 1 1 0 0 1 0 1 0 1 0 0 1

12 0 1 1 1 0 0 1 0 0 0 0 0

13 1 1 3 0 0 1 1 0 1 0 0 0

14 0 0 0 0 0 0 1 0 0 0 0 0

15 1 0 0 2 0 1 1 0 0 1 0 1

16 1 0 0 1 0 0 0 0 0 1 0 0

17 0 0 0 0 0 0 1 0 0 2 0 0

18 0 0 0 0 0 0 1 0 0 1 0 0

19 1 3 1 0 2 2 2 3 0 1 2 1

20 1 8 1 0 6 0 0 3 1 2 3 0

WHO/BS/2016.2294

14

TABLE 4

ISI after excluding outliers >±3SD

Lab ISI values

Candidate 14/001 Candidate 15/001

Reference:

rTF/09

Reference:

RBT/05

Reference:

rTF/09

Reference:

RBT/05

1 1.079 1.070 1.266 1.254

2 1.135 1.289 1.068 1.226

3 1.052 1.094 1.149 1.194

4 1.091 1.037 1.262 1.218

5 1.068 1.086 1.179 1.198

6 1.093 1.152 1.082 1.141

7 1.123 1.124 1.154 1.155

8 1.122 1.218 1.128 1.225

9 1.087 1.117 1.203 1.242

10 1.118 1.188 1.129 1.184

11 1.093 1.053 1.231 1.184

12 1.070 1.046 1.215 1.198

13 1.082 1.039 1.280 1.253

14 1.093 1.139 1.193 1.249

15 1.073 1.130 1.257 1.334

16 1.088 1.171 1.174 1.230

17 1.105 1.080 1.178 1.172

18 1.073 1.115 1.184 1.232

19 1.078 1.211 1.073 1.237

20 1.106 0.988 1.224 1.067

Mean 1.091 1.117 1.181 1.210

CV (interlab) 2.0 6.6 5.4 4.5

WHO/BS/2016.2294

TABLE 5

ISI (final) after excluding outliers >±3SD and INR<1.5 and INR>4.5 (Reference: rTF/09).

N is the number of normal and patients’ samples. CV(b) is the coefficient of variation of the

orthogonal regression line slope. CV is the between-laboratory coefficient of variation.

Lab Candidate 14/001 Candidate 15/001

N ISI CV(b) N ISI CV(b)

1 77 1.080 1.2 77 1.255 2.8

2 78 1.139 1.2 78 1.066 2.0

3 79 1.054 2.2 79 1.149 2.9

4 79 1.090 1.7 78 1.264 2.7

5 78 1.063 1.7 80 1.179 3.0

6 80 1.093 2.0 80 1.082 2.4

7 75 1.136 1.9 76 1.138 2.7

8 80 1.122 0.7 79 1.128 2.0

9 77 1.088 1.0 79 1.208 2.0

10 78 1.118 1.9 79 1.129 2.9

11 78 1.095 1.4 78 1.242 2.7

12 78 1.069 1.0 79 1.215 1.6

13 75 1.074 1.2 78 1.274 3.0

14 80 1.093 1.4 79 1.193 2.1

15 79 1.073 0.7 79 1.257 1.2

16 79 1.088 1.9 80 1.174 2.7

17 80 1.105 1.9 79 1.178 2.8

18 80 1.073 1.3 79 1.184 2.0

19 75 1.082 2.2 75 1.073 2.4

20 78 1.110 1.4 82 1.206 4.2

Mean 1.092 1.18

CV (%) 2.1 5.4

WHO/BS/2016.2294

16

TABLE 6

ISI (final) after excluding outliers >±3SD and INR<1.5 and INR>4.5 (Reference: RBT/05).

N is the number of normal and patients’ samples. CV(b) is the coefficient of variation of the

orthogonal regression line slope.


N ISI CV(b) N ISI CV(b)

1 77 1.075 2.5 77 1.254 1.4

2 71 1.357 2.6 74 1.228 2.3

3 79 1.096 2.3 80 1.194 1.9

4 79 1.037 2.3 79 1.218 1.9

5 79 1.086 2.5 79 1.198 1.7

6 80 1.152 2.5 78 1.141 1.5

7 77 1.146 4.2 78 1.153 3.4

8 78 1.233 2.0 79 1.225 1.0

9 79 1.119 1.8 79 1.242 1.1

10 79 1.188 2.8 79 1.184 1.5

11 79 1.056 2.4 79 1.189 1.6

12 79 1.046 1.5 80 1.198 1.2

13 79 1.050 2.7 80 1.253 1.6

14 80 1.139 2.1 80 1.249 1.4

15 77 1.130 1.1 78 1.334 0.9

16 79 1.171 2.8 79 1.230 1.5

17 80 1.080 2.1 78 1.172 1.8

18 80 1.115 2.0 79 1.232 1.7

19 76 1.240 2.6 76 1.240 2.1

20 83 0.994 2.9 82 1.062 2.9

Mean 1.125 1.210

CV (%) 7.5 4.5

WHO/BS/2016.2294

TABLE 7

Parameters of orthogonal regression line for patients’ samples only



a´ b´ a´ b´ a´ b´ a´ b´

1 0.138 0.965 -1.266 1.277 0.958 0.791 -0.242 1.060

2 0.134 0.983 -1.237 1.223 0.233 1.034 -1.197 1.281

3 -0.164 1.047 -1.928 1.446 0.899 0.795 -0.351 1.073

4 -0.003 1.009 -1.189 1.295 0.667 0.862 -0.280 1.088

5 0.107 0.976 -1.731 1.406 1.060 0.748 -0.281 1.059

6 0.264 0.931 -1.309 1.282 0.828 0.817 -0.667 1.155

7 -0.367 1.123 -1.332 1.274 0.500 0.936 -0.493 1.113

8 -0.007 1.023 -1.727 1.388 0.739 0.876 -0.621 1.158

9 0.140 0.976 -1.289 1.289 0.844 0.828 -0.344 1.087

10 0.094 0.986 -1.791 1.402 1.081 0.777 -0.353 1.092

11 0.107 0.984 -0.953 1.220 0.654 0.859 -0.168 1.036

12 0.075 0.987 -1.489 1.350 0.846 0.803 -0.441 1.104

13 0.140 0.974 -2.656 1.661 1.398 0.679 -0.429 1.127

14 0.004 1.012 -1.525 1.344 0.824 0.817 -0.431 1.091

15 0.002 1.001 -1.103 1.224 0.442 0.936 -0.480 1.117

16 -0.056 1.030 -2.101 1.520 1.114 0.761 -0.180 1.059

17 -0.072 1.030 -1.263 1.288 1.043 0.742 -0.375 1.075

18 0.081 0.987 -1.131 1.230 0.320 0.957 -0.846 1.191

19 0.059 1.003 -1.384 1.283 0.697 0.891 -0.755 1.186

20 0.023 1.005 -2.033 1.460 1.416 0.675 -0.115 1.016

WHO/BS/2016.2294

18

TABLE 8

Deviation (%) of INR values using orthogonal regression line parameters a´ and b´


Reference: rTF/09 Reference: RBT/05 Reference: rTF/09 Reference: RBT/05

INR = 2 INR=4.5 INR = 2 INR=4.5 INR = 2 INR=4.5 INR = 2 INR=4.5

1 -1.6 1.2 -8.5 6.0 4.9 -2.6 -1.4 0.9

2 -4.4 1.3 -8.7 2.3 11.3 -4.9 11.8 -2.3

3 3.4 -2.4 -10.0 5.8 13.3 -8.7 1.7 -0.9

4 -0.6 -0.7 -3.0 0.7 5.9 -2.2 1.0 -1.1

5 -0.4 0.1 -13.0 7.6 11.9 -6.8 0.7 -0.6

6 -3.2 3.7 -9.2 9.1 8.2 -9.5 6.1 -5.4

7 1.7 -3.5 -1.8 3.6 4.7 -9.1 2.6 -5.3

8 -0.6 0.6 -9.3 8.7 9.8 -10.3 3.8 -2.7

9 -1.3 1.2 -8.0 6.0 6.0 -4.9 0.2 -0.4

10 -2.1 1.9 -13.0 13.6 9.4 -11.1 2.1 -2.5

11 -1.5 0.8 -3.2 2.3 3.5 -1.3 0.4 0.3

12 -0.2 -0.1 -4.5 6.3 5.9 -7.7 2.0 -2.6

13 -1.1 0.4 -16.3 10.7 16.3 -8.2 1.7 -1.0

14 -0.2 -0.3 -9.1 7.9 7.4 -7.1 0.3 -0.0

15 0.5 -0.2 -3.0 0.9 2.9 -1.3 -2.5 0.6

16 1.1 -0.9 -14.9 11.9 13.3 -10.1 -0.3 0.4

17 0.6 -0.1 -12.7 8.3 8.0 -4.7 2.2 -2.1

18 -0.3 0.1 -0.6 0.5 6.6 -2.6 6.7 -1.6

19 -0.2 -0.5 -8.4 8.5 5.6 -12.2 3.1 -4.2

20 -0.8 0.9 -8.9 14.4 10.0 -9.1 2.3 -5.0

Mean -0.6 0.2 -8.3 6.8 8.2 -6.7 2.2 -1.8

WHO/BS/2016.2294

TABLE 9

Mean ISI before and after exclusion of non-valid assessments. SD and CV is the between-

laboratory standard deviation and coefficient of variation, respectively. SE is the standard

error of the mean (= SD/√N).

Lab Before exclusion After exclusion


Ref:

rTF/09

Ref:

RBT/05

Ref:

rTF/09

Ref:

RBT/05

Ref:

rTF/09

Ref:

RBT/05

Ref:

rTF/09

Ref:

RBT/05

1 1.080 1.075 1.255 1.254 1.080 1.075 1.255 1.254

2 1.139 1.357 1.066 1.228 1.139 1.357

3 1.054 1.096 1.149 1.194 1.054 1.096 1.194

4 1.090 1.037 1.264 1.218 1.090 1.037 1.264 1.218

5 1.063 1.086 1.179 1.198 1.063 1.198

6 1.093 1.152 1.082 1.141 1.093 1.152 1.082 1.141

7 1.136 1.146 1.138 1.153 1.136 1.138

8 1.122 1.233 1.128 1.225 1.122 1.233 1.225

9 1.088 1.119 1.208 1.242 1.088 1.119 1.208 1.242

10 1.118 1.188 1.129 1.184 1.118 1.184

11 1.095 1.056 1.242 1.189 1.095 1.056 1.242 1.189

12 1.069 1.046 1.215 1.198 1.069 1.046 1.215 1.198

13 1.074 1.050 1.274 1.253 1.074 1.253

14 1.093 1.139 1.193 1.249 1.093 1.139 1.193 1.249

15 1.073 1.130 1.257 1.334 1.073 1.130 1.257 1.334

16 1.088 1.171 1.174 1.230 1.088 1.230

17 1.105 1.080 1.178 1.172 1.105 1.178 1.172

18 1.073 1.115 1.184 1.232 1.073 1.115 1.184 1.232

19 1.082 1.240 1.073 1.240 1.082 1.240 1.240

20 1.110 0.994 1.206 1.062 1.110 1.062

Mean 1.092 1.125 1.180 1.210 1.092 1.138 1.201 1.212

CV (%) 2.1 7.5 5.4 4.5 2.1 8.0 4.6 4.6

Mean all 1.109 1.195 1.110 1.208

SD 0.0632 0.0605 0.0629 0.0552

CV (%) 5.7 5.1 5.7 4.6

SE 0.0100 0.0096 0.0109 0.0103

WHO/BS/2016.2294

20

TABLE 10

Mean INR and between-laboratory standard deviation for control plasmas A, B, C, and D

Plasma A Plasma B Plasma C Plasma D

rTF/09 0.95 ± 0.05 1.99 ± 0.12 2.92 ± 0.19 4.35 ± 0.35

Candidate 14/001 0.94 ± 0.03 2.00 ± 0.11 3.00 ± 0.19 4.51 ± 0.35

RBT/05 0.98 ± 0.04 2.18 ± 0.14 2.96 ± 0.20 4.18 ± 0.28

Candidate 15/001 0.98 ± 0.04 2.22 ± 0.12 3.03 ± 0.19 4.26 ± 0.34

WHO/BS/2016.2294

TABLE 11

Mean prothrombin time and prothrombin time ratio with candidate 14/001 after storage at

various temperatures. The PT ratio was calculated as the mean PT of plasma AP141204

divided by the mean PT of plasma NP141202.

Storage temperature: +5°C Storage temperature: +31°C

Storage

time (d)

Mean PT (s) PT ratio Storage

time (d)

Mean PT (s) PT ratio

NP141202 AP141204 NP141202 AP141204

0 12.33 32.27 2.617 0 12.33 32.90 2.668

1 12.30 31.80 2.585 1 12.30 31.70 2.577

2 12.30 32.03 2.604 2 12.23 31.37 2.565

3 12.30 31.97 2.599 3 12.17 31.33 2.574

4 12.07 32.07 2.657 4 12.30 30.23 2.458

7 12.77 32.57 2.551 7 12.40 30.33 2.446

14 12.27 31.60 2.575 14 12.27 30.70 2.502

21 12.30 32.93 2.677 21 11.93 29.93 2.509

28 12.33 32.73 2.655 28 12.47 29.17 2.339

42 12.57 32.07 2.551 42 12.23 29.40 2.404

56 12.30 32.33 2.628 56 12.27 29.60 2.412

p-value‡ 0.695 0.174 0.770 p-value 0.687 <0.001 <0.001


Storage

time (d)


time (d)


NP141202 AP141204 NP141202 AP141204

0 12.53 33.23 2.652 0 12.37 32.20 2.603

1 12.13 30.33 2.500 1 11.9 29.50 2.479

2 12.00 29.67 2.473 2 11.63 29.57 2.543

3 12.07 29.93 2.480 3 11.83 28.93 2.445

4 11.77 29.57 2.512 4 11.83 28.47 2.407

7 11.60 28.67 2.472 7 11.20 27.73 2.476

14 11.37 28.83 2.536 14 11.47 27.20 2.371

21 11.70 28.30 2.419 21 11.20 27.10 2.420

28 11.67 27.83 2.385 28 11.00 26.20 2.382

42 11.33 27.20 2.401 42 10.80 25.43 2.355

56 11.23 26.93 2.398 56 11.07 26.67 2.409

p-value‡ <0.001 <0.001 0.005 p-value <0.001 <0.001 0.004

‡ Spearman’s bivariate correlation between storage time and mean PT or PT ratio

WHO/BS/2016.2294

22

TABLE 12

Mean prothrombin time and prothrombin time ratio with candidate 15/001 after storage at

various temperatures. The PT ratio was calculated as the mean PT of plasma AP141204



Storage

time (d)


time (d)


NP141202 AP141204 NP141202 AP141204

0 18.30 41.77 2.282 0 18.2 41.37 2.273

4 18.23 40.7 2.232 3 18.57 41.57 2.238

5 18.43 41.5 2.251 4 18.97 42.97 2.265

6 18.40 41.5 2.255 5 18.7 43.13 2.307

7 18.20 40.63 2.233 6 18.73 43.4 2.317

9 18.6 41.23 2.217 8 18.73 42.97 2.294

17 18.63 41.4 2.222 15 19.37 44.47 2.296

24 18.2 41.2 2.264 22 19.27 44.2 2.294

31 18.5 41.1 2.222 28 19.97 45.67 2.287

44 18.4 41.67 2.264 43 19.97 45.87 2.297

59 18.47 41.73 2.260 57 20.27 47.63 2.350

p-value‡ 0.303 0.926 0.915 p-value <0.001 <0.001 0.056


Storage

time (d)


time (d)


NP141202 AP141204 NP141202 AP141204

0 18.1 40.87 2.258 0 18.1 41.43 2.289

2 18.87 42.53 2.254 1 19.3 43.53 2.256

3 19.1 43.83 2.295 2 19.23 43.53 2.263

4 19.9 43.8 2.201 3 19.67 44.23 2.249

5 19.1 43.77 2.291 4 19.57 44.4 2.269

7 19.03 43.63 2.293 6 19.4 44.23 2.280

15 19.83 45.8 2.310 13 20.1 45.83 2.280

22 20.07 46.57 2.321 20 21.1 47.53 2.253

29 20.07 46.77 2.331 26 21.33 48.7 2.283

42 20.5 47.57 2.320 41 21.43 50.73 2.367

57 21.37 49.93 2.337 55 22.17 51.97 2.344

p-value‡ <0.001 <0.001 0.001 p-value <0.001 <0.001 0.133


WHO/BS/2016.2294

TABLE 13

Mean prothrombin time and prothrombin time ratio at various times after reconstitution

of candidate 14/001. The PT ratio was calculated as the mean PT of plasma AP141204


Time (h) Mean PT ± standard deviation (s) PT ratio

NP141202 AP141204 AP/NP

0.5 12.33 ± 0.31 33.42 ± 0.82 2.709

1 12.50 ± 0.18 33.87 ± 0.54 2.709

2 12.60 ± 0.11 33.65 ± 0.24 2.671

3 12.43 ± 0.27 34.08 ± 0.41 2.741

4 12.40 ± 0.30 33.87 ± 0.39 2.731

p-value‡ 0.873 0.219 0.391


WHO/BS/2016.2294

24

TABLE 14

Mean prothrombin time and prothrombin time ratio at various times after reconstitution

of candidate 15/001. The PT ratio was calculated as the mean PT of plasma AP141204


Time (h) Mean PT ± standard deviation (s) PT ratio

NP141202 AP141204 AP/NP

0.5 17.83 ± 0.28 42.15 ± 0.23 2.364

1 17.60 ± 0.32 41.17 ± 0.62 2.339

2 17.55 ± 0.15 40.97 ± 0.39 2.334

3 17.40 ± 0.14 40.38 ± 0.53 2.321

4 17.47 ± 0.21 40.55 ± 0.40 2.322

p-value‡ 0.037 0.037 0.037


WHO/BS/2016.2294

WHO/BS/2016.2294

26

WHO/BS/2016.2294

WHO/BS/2016.2294

28

WHO/BS/2016.2294

WHO/BS/2016.2294

30

EXPERT COMMITTEE ON BIOLOGICAL STANDARDIZATION...3264; fax: +41 22 791 4857; e-mail:...

Documents

Transcript of EXPERT COMMITTEE ON BIOLOGICAL STANDARDIZATION...3264; fax: +41 22 791 4857; e-mail:...