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Assuring the Quality of Samples for Proficiency Testing or External Quality Assessment Schemes

Assuring the Quality of Samples for Proficiency Testing or External Quality Assessment Schemes. Aim. To explain how to ensure the quality of samples for an External Quality Assessment Scheme. Outline of Presentation. Issues involved in sample preparation

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Assuring the Quality of Samples for Proficiency Testing or External Quality Assessment Schemes

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  1. Assuring the Quality of Samples for Proficiency Testing or External Quality Assessment Schemes

  2. Aim • To explain how to ensure the quality of samples for an External Quality Assessment Scheme

  3. Outline of Presentation • Issues involved in sample preparation • Distributing panels to EQAS participants in SEA/WP

  4. Ensuring the quality of EQAS samples: Issues to be considered • 2. Material (sample bank) • collect samples • characterise samples • maintain database • 1. Resources • laboratory facilities, train staff • equipment, space • material • 4. Sample distribution • produce documents • coordinate shipping • review sample state • 3. Panel preparation • pose a ‘question’ • select samples from the Bank • retest samples, prepare panel

  5. Preparing quality EQAS samples • Try and decide: • Who? • What? • Where? • When? • Why? • How?

  6. Ensuring the quality of EQAS samples: Issues to be considered • 2. Material (sample bank) • collect samples • characterise samples • maintain database • 1. Resources • laboratory facilities, train staff • equipment, space • material • 4. Sample distribution • produce documents • coordinate shipping • review sample state • 3. Panel preparation • pose a ‘question’ • select samples from the Bank • retest samples, prepare panel

  7. 1. Resources required to coordinate an EQAS - Laboratory Samples need to be tested Therefore provider should have access to a: • laboratory with testing facilities *provider may contract out laboratory services • laboratory with technical competence • participate in other EQAS • hold accreditations

  8. 1. Resources required to coordinate an EQAS - Trained Staff • Provider should train staff in EQAS procedures • significant amount of time is required to train staff during EQAS development • Staff need to: • coordinate sample bank, perform testing • prepare panels, coordinate shipments • communicate with participants • be prepared to educate participants

  9. 1. Resources required to coordinate an EQAS - Equipment and Space Provider should have access to: • equipment required for testing of serology samples • general items such as: • fridge, freezers, bottles • vials, shipping boxes • space • for packaging samples for distribution • for general purpose storage

  10. 1. Resources required to coordinate an EQAS - Biological Material Providers must develop and maintain a sample bank: • Significant resources required during development • source material • characterise new samples • develop data base • Continual resources to maintain

  11. Ensuring the quality of EQAS samples: Issues to be considered • 2. Material (sample bank) • collect samples • characterise samples • maintain database • 1. Resources • laboratory facilities, train staff • equipment, space • material • 4. Sample distribution • produce documents • coordinate shipping • review sample state • 3. Panel preparation • pose a ‘question’ • select samples from the Bank • retest samples, prepare panel

  12. 2. Sample Bank Collection of biological material (1) • large volumes • best possible quality • plasma or serum? • thrombinisation and recalcification • technically difficult • risk of bacterial contamination

  13. 2. Sample Bank Collection of biological material (2) • Representative of the geographical area • Unusual samples • may be required to purchase • Collect from • collaborating laboratories • participants • purchase

  14. 2. Sample Bank Processing and storage of material • Allocate material with unique identifier • Aliquot material into smaller volumes • Monitor freeze/thaw cycles • Use polypropylene tubes and bottles • Label all bottles/tubes • Store at -20C or -40C

  15. 2. Sample Bank Characterisation of material • Test according to testing strategy • determine disease status • WHO recommend: • two immunoassays (2nd with different Ags) • one specific supplemental assay • Similar technology to assays used in region

  16. 2. Sample Bank Store data on all material in sample bank • Store sample information in a Database • For each sample store: • volume available and location • information provided with the material • characterisation results • assays used, S/Co ratio, disease status • other information, e.g. subtype/genotype

  17. Ensuring the quality of EQAS samples: Issues to be considered • 2. Material (sample bank) • collect samples • characterise samples • maintain database • 1. Resources • laboratory facilities, train staff • equipment, space • material • 4. Sample distribution • produce documents • coordinate shipping • review sample state • 3. Panel preparation • pose a ‘question’ • select samples from the Bank • retest samples, prepare panel

  18. 3. Panel Preparation Design each panel to ask a “question” Specific questions that may be addressed: • Do Laboratories: • identify the status of samples correctly? • produce consistent results? • follow their testing strategies? • follow the manufacturers protocol? • check samples are correctly labelled?

  19. 3. Panel Preparation Selection of EQAS Panel samples (1) • Review sample bank database • Select 8-10 specimens • with a definite serostatus • strongly reactive, weakly reactive and negative • select different numbers of positive and negative samples for each panel

  20. 3. Panel Preparation Selection of EQAS Panel samples (2) • Replicates • Diluted and pooled samples • increases the available volume • such samples are not representative of true samples

  21. 3. Panel Preparation Preparation of EQAS Panel samples (1) • Biocides • Not recommended but can use Bronidox L (0.05%) • Heat Inactivation • 60 minutes at 56ºC for HIV • Better to treat everything as infectious EQAS samples should be representative of routine diagnostic specimens

  22. 3. Panel Preparation Preparation of EQAS Panel samples (1) • Lyophilisation • May be necessary if transport conditions indicate • Requires expensive equipment EQAS samples should be representative of routine diagnostic specimens

  23. 3. Panel Preparation Preparation of EQAS Panel samples (2) • Ensure traceability • use checklists, record who did what and when • Remove material from sample bank • thaw, if material was stored in >1 bottle - pool • centrifuge • re-test sample to ensure serostatus has not changed • specific confirmatory test e.g. Western blot

  24. 3. Panel Preparation Preparation of EQAS Panel samples (3) • Tube integrity and labelling • leak proof screw capped plastic tubes • good quality labels, electronically prepared • segregated tube labelling

  25. 3. Panel Preparation Preparation of EQAS Panel samples (3) • Aliquot material • segregated aliquotting • only one sample in hood at one time • store panel at 4º, dispatch as soon as possible

  26. 3. Panel Preparation Sample Validation: Homogeneity Testing • Panel samples should be tested to ensure that they are homogenous. Homogenous (evenly distributed) Non-Homogenous

  27. 3. Panel Preparation Sample Validation: Stability Testing • Panel samples should be tested to ensure that their reactivity is stable over time Unstable

  28. Ensuring the quality of EQAS samples: Issues to be considered • 2. Material (sample bank) • collect samples • characterise samples • maintain database • 1. Resources • laboratory facilities, train staff • equipment, space • material • 4. Sample distribution • produce documents • coordinate shipping • review sample state • 3. Panel preparation • pose a ‘question’ • select samples from the Bank • retest samples, prepare panel

  29. 4. Sample Distribution • Documentation to be included with the panel i) Covering letter • identifies the sample details • gives instructions for testing • designated the due date for return of results ii) Result forms iii) Ask laboratories to confirm: • that samples were received • confirm contact and shipping address details

  30. 4. Sample Distribution Co-ordinate panel distribution • Panels should be distributed in accordance with IATA regulations for other regulation for shipping dangerous goods • Ensure all documents are supplied

  31. Shipping of samples to the South East Asian and Western Pacific Regions: Anti-HIV, anti-HCV and HBsAg. National Serology Reference Laboratory, Australia

  32. The NRL experience Problems encountered • Complex contact details • Complex paperwork • Complex communications

  33. The NRL experience Problems encountered • Results are often not returned by some participants • Obtaining accurate information from participants is often difficult and time consuming

  34. The NRL experience Tips for minimizing shipping costs • Cost savings: • good courier company • collaborators picking up samples from the airport • collaborators redistributing samples within one country

  35. Summary • Good quality samples are required for participants to have confidence in the EQAS. • Best quality samples are planned for at each step of the EQAS. • Resources are required to achieve the best possible quality samples

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