What is External Quality Assessment

External Quality Assessment (EQA) sometimes referred to as Proficiency Testing (PT) is an essential aspect of any laboratory operation providing a means of assessing analytical performance compared to other laboratories using the same method and instrument.

EQA is designed to retrospectively monitor laboratory performance using 'blind' samples analysed as if they were patient samples. EQA results are submitted to the scheme organiser on a regular basis for statistical analysis; each individual laboratory will then receive a report comparing their performance to others participating in the same programme.

A program in which multiple samples are periodically sent to members of a group of laboratories for analysis and/or identification; whereby each laboratory’s results are compared with those of other laboratories in the group and/or with an assigned value, and reported to the participating laboratories and others. CLSI GP27-A2 27:8
....a system of objectively checking laboratory results by means of an external agency.... WHO External Assessment of Health Laboratories (1981)

The main objective of EQA or PT is to develop inter-laboratory comparability and standardisation of diagnostic testing. In addition to this EQA can provide laboratories with the necessary information to help them:

  • Maintain and improve analytical quality
  • Improve inter-laboratory agreement and raise standards
  • Detect equipment faults, identify reagent problems and review staff training
  • Initiate and evaluate corrective actions
  • Compare performance to different analytical methods

Ongoing monitoring of EQA performance using an effective EQA scheme like RIQAS will help to reduce laboratory errors, produce accurate patient test results and most importantly improve patient care.

Regulatory requirements

Both national regulatory bodies and international standards encourage participation in a reputable EQA provider like RIQAS.

The laboratory shall participate in inter-laboratory comparisons such as those organised by external quality assessment schemes. Laboratory management shall monitor the results of external quality assessment and participate in the implementation of corrective actions when control criteria are not fulfilled. Inter-laboratory comparison programmes shall be in substantial agreement with ISO/IEC Guide 43-1 ISO15189 section 5.6.4

Ideal specifications of an EQA provider

An ideal EQA programme provider should provide the following:

  • International accreditation
  • ‘Blind’ samples
  • Large participant numbers
  • Stable and consistent sample matrix
  • Sample matrix similar to patient sample
  • Realistic range of analyte concentrations
  • Frequent analysis
  • Rapid feedback
  • Detailed reports
EQA should, as far as possible, cover the entire range of tests, and the entire examination process, from sample reception, preparation and analysis to interpretation and reporting. ISO 15189