Laboratory Administration & Management of Pathology Practices

• External quality assessment (EQA) is a system for objectively checking laboratory performance using an external agency or facility
• Proficiency testing (PT) is one method for achieving this
  • PT is educational and promotes continuous learning; it supports laboratories in implementing new biomarkers into clinical testing as well as maintaining quality for existing biomarkers
  • PT fulfills a different function from laboratory accreditation although the two are complementary; participation in PT is usually required for laboratory accreditation

• PT can be arranged in different ways and can differ on how the test results are compared and scored
• For most of the biomarkers, laboratories report the results to the organization that provides PT challenges
• Results are compared to either designated "true value" or "consensus score / results"
  • Reasons for using one or the other method in evaluation of laboratory performance may be complex and often depend on the type of the assay used for the biomarker
    • Different approaches may be used for qualitative markers for which reference standards are well defined and readily available (e.g. blood glucose testing)
    • Descriptive methodologies would require designated descriptive true value for which no reference standards could be developed and do not exist (e.g. ER and PR testing in breast cancer)
• Although not possible for all biomarkers, it is highly desirable for PT organizations to use a known, qualified reference sample that is very similar to clinical samples
  • This is provided by the external third party for their challenges
    • Since this is often not available, a second best option is artificial samples ; for example ctDNA mutation testing using synthetically prepared DNA spiked into plasma
  • These reference samples are first qualified by the PT provider to confirm their biomarker status, then are sent to the participating laboratory for testing
  • Laboratories run these samples through their normal diagnostic process, as they would standard clinical samples
  • Organizations providing PT usually report to the participant whether the laboratory passed or failed the challenge
  • They may or may not provide feedback to the laboratory on possible technical issues that could have influenced the suboptimal or poor results or suggestions for improvements

It is also important to consider what or how the readout of the test is performed

• If the readout process is automated (e.g. glucose testing), there will be no need and no possibility for central review
  • Participating laboratories will send their results to the PT provider
• If the readout is interpretive, for example done by pathologists (e.g. ER and PR for breast cancer), the IHC results include both elements of the slide staining and the pathologist's readout
• Slides may be sent to the PT provider without the local pathologist's readout thereby only assessing the slide staining component
• Laboratories could also report the pathologist's readout results only without sending the slides
• They also could send the slides back and provide the local pathologist's readout
• Therefore, both protocol performance (the quality of IHC slide staining) and the readout performance (the quality of pathologist's readout) impact final results of IHC testing or both could be the subject of PT evaluation

In practical terms, using IHC biomarkers as an example, PT is usually performed in two different ways:

1. PT with central sample review
   • IHC slides are reviewed in the participating laboratory and the results are reported to the PT provider
   • When the IHC slides are sent back to PT provider, the PT provider performs a central review of the slides
   • This central review is usually done by experienced pathologists and technologists who reach a consensus “true” result
   • Independent providers verify the results from the laboratories by comparison to the validated “true” central review result and feed back discrepancies to the laboratory
2. PT with consensus scoring
   • Similar to above, except the PT provider does not perform a central review
   • Laboratories run the test slides and perform the readout locally
   • Laboratories do not need to return the IHC slides to the PT provider since no central review will be performed
   • PT providers use a process to determine the consensus score and designate this as the designated correct result or truth set
   • This method is less objective and can occasionally be problematic, especially when many laboratories return an incorrect result
   • In this approach, the laboratories gain insight on how similar they are to other participants: designated as "concordance"

WHO recently released guidelines for national EQA schemes - laboratories are highly encouraged to join EQA schemes that follow the WHO best practice guidelines (WHO: WHO Manual for Organizing a National External Quality Assessment Programme for Health Laboratories and Other Testing Sites [Accessed 5 November 2017])

• Quality assessment is a critical aspect of laboratory quality management
  • Laboratories which hold an accreditation such as CAP or ISO 15189 are required to participate in an appropriate PT, where available
  • Passing PT is not a replacement for laboratory accreditation as PT and accreditation fulfill different functions
    • Laboratories test thousands of samples per week, every week of the year
    • Continuous followup of laboratory performance over time is needed as many factors can influence laboratory operations:
      • New reagents
      • New methods
      • Change in staff etc.
    • In this regard, PT is different from accreditation because it is a continuous process, whereas accreditation reflects an assessment of standards in laboratories at a specific time
• PT is mandatory in some countries and not in others
  • This may change as there is an increasing awareness of the benefits of participating in PT
  • Even in jurisdictions that do not mandate PT, laboratories should consider voluntary participation and join PT programs offered locally, nationally or internationally for the biomarker tests they offer because of the many benefits gained from the participation
• Different PT providers offer a range of programs and laboratories can now easily participate in PT programs from other countries if local providers do not cover the biomarkers of interest
• To easily find information about different PT providers, visit the IQN Path webpage

What are the 3 main advantages of laboratory participation in EQA?

1. EQA provides a mechanism for laboratory self checking
2. EQA is an opportunity for continuous learning by testing laboratories
3. EQA provides a substitute for accreditation
4. EQA provides a substitute to establishing a laboratory quality management system
5. EQA provides support during a time of new assay validation and verification prior to offering a test in a clinical setting

A, B, E. The three main advantages of laboratory participation are: EQA provides a mechanism for laboratory self checking, EEQA is an opportunity for continuous learning by testing laboratories and EQA provides support during a time of new assay validation and verification prior to offering a test in a clinical setting.

Comment Here

Reference: External quality assessment and proficiency testing