External Quality Assessment (EQA) and Proficiency Testing (PT) are valuable tools in the quality improvement process. They provide objective evidence of laboratory competence for customers, accrediting bodies, and regulatory agencies, and serve as a unique source of information that is not obtainable in other ways. In particular, internal quality control (IQC) and external quality assessment (EQA) programs are used to evaluate and continuously improve analytical quality. Currently, the terms External Quality Assessment (EQA) and Proficiency Testing (PT) are used interchangeably as valuable tools in the quality improvement process of clinical laboratory services.

According to a widely-accepted definition, PT is “a program in which multiple samples are periodically sent to members of a group of laboratories participating for analysis and/or identification, in which each laboratory results are compared with those of other laboratories in the group and/or with assigned value, and reported to the participating laboratory and others”. On the other hand, the best definition of EQA is “an integrated professional quality assurance activity of medical laboratories”. For medical laboratories, they have been found useful, in that they initiates a “peer-review” process towards solving technical and methodological problems to improve the quality of service for each individual laboratory as well as to achieve comparability of results among different laboratories. For accrediting bodies and regulatory agencies, they provide objective data on the quality of delivered services as EQA/PT performance has been shown to reflect the quality of patient specimen testing. The contents reported in this paper relate equally to PT and EQA, and for that reason the term EQA/PT will be used even if it is graceless.