External quality assurance (EQA) testing schemes are a tool that allows participants to monitor, evaluate and improve their own performance. Participation involves receiving samples at regular intervals from an external body, testing them by the same routine methods used for normal referrals and reporting the results to the EQA organising centre. In the UK, H&I laboratories participate in the UK National External Quality Assessment Service scheme for H&I (UK NEQAS for H&I) for all services they offer. This is a requirement of CPA and EFI accreditation. They may also optionally take part in the Terasaki HLA testing schemes.
The UK NEQAS for H&I includes scheme 1A – HLA phenotyping by serology, scheme 1B – HLA B27 typing, scheme 2A – cytotoxic crossmatching, scheme 2B – crossmatching by flowcytometry, scheme 3 – HLA antibody specificity analysis, scheme 4A1 – DNA HLA Typing at 1st Field Resolution, scheme 4A2 – DNA HLA Typing at 2nd Field Resolution, scheme 4B – ABO grouping by DNA based methods, scheme 5A – HFE typing, scheme 5B – HFE interpretation, scheme 6 – HLA antibody detection and scheme 7 – HLA B*57:01 typing and an educational scheme.
Each of the UK NEQAS schemes releases a number samples for testing through the course of the year. The results of each round are assessed based on consensus. In general, where 75% or more of laboratories agree a result, then that result is taken to be true. One exception is scheme 3 – HLA antibody specificity analysis, where 95% of laboratories must agree that a specificity is absent for that to be considered true. Where no consensus is reached, that particular round of tests is not scored. Each laboratories performance for each round of samples is judged to be Acceptable or Unacceptable based on whether or not their results agreed with the consensus. At the end of the year, the laboratories overall performance for each scheme is judged as Satisfactory or Unsatisfactory based on achieving a specified number of Acceptable performances.
Through the year, each laboratory receives an analysis of their individual results both for current specimens and their results for the year so far. They also receive anonymised results from all other laboratories together with an indication of the techniques used by those laboratories. This allows them to assess their performance relative to other laboratories. Laboratories with poor performance are required to detail the corrective and preventative measures they intend to put in place to improve their results. The UK NEQAS organisers can provide help and advice to laboratories should it be requested.
Participation in these schemes are an important aspect of quality management in an H&I laboratory. The benefits of participation are that it helps demonstrate to colleagues and to customers/Users the laboratories commitment to quality. It also provides the laboratory management with an insight into the performance of the laboratory. Participation in NEQAS acts as a stimulus for improvement helping to drive up standards in the laboratory. It may help reveal unsuspected areas of difficulty and act as a check on the efficacy of internal quality control procedures. In addition, it can be used as a tool for competence assessment of laboratory staff. Ultimately participation in EQA schemes is a requirement of CPA and EFI accreditation.
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