Problems with Standardisation of Automated Titration Local Level Implementation - ISO 15189

Transcription

1 Problems with Standardisation of Automated Titration Local Level Implementation - ISO 59 Yvonne Scott Transfusion Manager The Newcastle upon Tyne Hospitals NHS Foundation Trust BBTS 7

2 In Our Trust Who Needs Titrations O ABO incompatible Transplant O Heart O Renal O Bone Marrow O Antenatal O Regional Fetal Medicine Unit O IVIg Products

3 Historic O Direct Agglutination (DRT) Tube Technique O Wide range of results O Dependant on operator O Time consuming O Clinicians Focused on Target Titre to make decisions Current Demand O Rapid result O Often required peri-op O Pre and post plasmapheresis / column exchange O Staff issues O Most occur out of hours 3

4 BioVue Technology Manual AutoVue Innova or Ultra VISION / VISION Max Easy, Quick and Reliable

5 VISION / VISION Max Option to facilitate Automated serial dilutions (Automated Titration) Specific & Sensitive Easy Operation Ability to select individual panel cells (Antigen specific) 5

6 Cell Selection O Ability to select specific cell lines O Custom build profile to your requirements (DRT,IAT) O You select the cell profile required (hetero/homo) O Isohaemagglutinins DRT only - NO IAT available or is it! O BSH Compliant Reagents O Homozygous for Rh, Fya, Fyb, Jka, Jkb, M, and S antigens O Heterozygous cell available on all Panels O Other manufacturers reagents O Increases antigen profile (NHSBT, Quotient) 6

7 UKAS ISO 59 O Does it do what it says it does? O Reproducibility O Comparability O Between Analysers O Between Methodology (UKAS Scheme) O Uncertainty of Measurement O Trending O Turn around Times O NEQAS 7

8 Visual confirmation of serial dilution using a grossly haemolysed plasma sample. Graph showing measured and expected HI for a haemolysed sample, serially diluted on the VISION Haemolysis Index (HI) Expected Haemolysis Index (HI) 5 3 Measured Haemolysis Index (HI) Neat 6 Dilution 6 56

9 Reproducibility Anti-A Titre Anti-B Titre VISION IAT TUBE DRT Sample Test Number 9 VISION DRT 6 VISION DRT Titre Titre 6 VISION IAT TUBE DRT Sample Test Number 9 9

10 Reproducibility 73/55 Anti-D VISION IAT Titre /6 Anti-c VISION IAT Titre 6 6 Titre Titre Sample Test Number Sample Test Number

11 Comparability Pool PS Anti-A Pool PS Anti-B NIBSC Anti-D (73/55) Test VISION IAT VISION DRT VISION IAT VISION DRT VISION IAT FH V FH V RVI V RVI V Total Sum Number of Measurements Mean 6 SD %CV.57

12 Uncertainty of Measurement Pool PS Anti-A no. Tests VISION VISION IAT DRT NIBSC NIBSC Anti-D anti-c (73/55) (/6) Pool PS Anti-B TUBE DRT VISION VISION IAT DRT TUBE DRT VISION VISION IAT IAT Total Sum Number of Measurements Mean SD %CV

13 Trending 3

14 Turn Around Time Card / Tube Preparation Serial dilution (including pipetting into card) Red cell reagent pipetting Incubation Centrifugation Reading VISION Time (Min : Secs) : 6: :6 5:5 5:7 :7 MANUAL Time (Min : Secs) 3: Total Time :7 55: Unavailable to start other orders 7: 3: Volume aspirated from Primary sample Volume of dilution remaining in each well (unused) Our protocol: VISION - Minimum required for each serial dilution test Our protocol: MANUAL - Minimum required for each serial dilution test 6uL ul ul 9uL 5uL ul Process 9:3 : :

15 DRT Turn Around Time Turn Around Time :: AM :57:36 AM :5: AM Time (Mins) :3: AM :36: AM TUBE Time :: AM VISION Time ::36 AM :: AM :7: AM :: AM Sample Number 5

16 NEQAS ABO Titration O O O O ABO titration pilot since 9 Full UK NEQAS Scheme 7/ Scores for outlying results (more than dilution from target ) Standard Technique BioRad (DRT & IAT) O Considerable variation in results between techniques O Standard technique would facilitate transfer of results & transplant protocols across centres O Possible to use NIBSC WHO reference reagent (High titre Anti-A and Anti-B (/3)) to standardise titration methodology for anti-a and Anti-B to establish consistent cut-off values 6

17 NIBSC Anti-A & Anti-B /3 O Note: the testing of replicate dilution series of both /3 and the serum/plasma samples is recommended to take into account intra-laboratory variation in repeat titrations. O Calculate geometric mean titres for /3 and the samples i.e., the average of the base logarithmic values of each titre set, converted back to a base number. O By multiplying the ratio of the sample geometric mean to the geometric mean of /3 by the nominal titre assignment to /3, the relative titre of the sample can be determined. 7

18 I m going to try this! O Recommend multiple titrations of standard and sample O Standard gives ml (cost 9) O Need.5mL per titre O Can do titres of the standard! O May get more from the sample? O Financial constraint O Need Business Case to buy lots of standard O find out if dilution will work / can it be frozen once reconstituted? O Staff enthusiastic O Have to tell them not possible to do automated Titration yet! O I can O now use base logarithmic and antilog calculators O know what a geometric mean and relative titre is.

19 We have tried it, does it Work? Plasma Test Titre Base Logarithmic Result =LOG(Titre,Base) DRT ORTHO VISION Analyser Anti-A Replications Reverse Diluent Cassette Total Sum Number of Measurements Mean SD %CV Geometric Mean NIBSC Anti-A assigned DRT value Sample Relative Titre Sample Result Base log result base log result

20 Anti-A Patient Results VISION IAT Actual Titre 56 6 Relative Titre VISION DRT TUBE DRT

21 Results so Far O /3, 73/55 and /6 NIBSC Standards data shows excellent inter/intra analyser reproducibility O More titres required on Anti-A and Anti-B /3 O Statistical analysis needed when sufficient data obtained esp. conversion to the Relative Titre. O Continue testing..(once we have Money) O Discuss with Clinicians what the new cut-off level is?

22 The Way Forward Automated Titration O Works O Good reproducibility O Good Comparability O Quick TAT O Eases staff pressures Inter-laboratory Testing O Need to work with other VISION users O Use NIBSC standard for our technique O Can we get a reproducible level / cut-off for BioVue Technology Analyser Improvements O Software improvement to perform IAT Isohaemagglutinins O Use one master dilution series for multiple titres e.g Group O O Anti-A DRT & IAT O Anti-B DRT & IAT

23 Question - Do we need an Absolute Result? The problem is not with automating titres O The problem is O O O O Standardising Methods in each Technology Obtaining a definitive result that is transferable between laboratories Changing Clinical Practice Not accruing points in the NEQAS exercises O Clinicians for ABOi Heart Transplants focus on trends as well as results O In the beginning a maximum titre of : pre procedure was acceptable O Currently have no maximum titre restriction O Plasma exchange to reduce the Isohaemagglutinin and facilitate crossing of ABO boundaries O Monitor Isohaemagglutinin trend to determine further exchange/treatment 3

24 Big Thanks to My Team (who do all the work) Chris Hall Alison Muir Michelle Evans The BMS staff at NUTH