Special issue on External Quality Assessment in Laboratory Medicine – current challenges and future trends

Quality assurance in the modern clinical laboratory is evidenced through the complementary processes of internal quality control and external quality assessment, also known as proficiency testing. By these processes and the achievement of accreditation to international (e.g. ISO) standards, the laboratory is able to demonstrate its competence to the users of its services, i.e. the clinicians and the patients they care for, who have an expectation that the results of diagnostic testing and monitoring of treatment are correct, comparable and fit-for- purpose within the scope of the service, wherever they are performed. External quality assessment (EQA) was first introduced in the 1950s and 1960s in response to the growing role of laboratory testing as an essential part of disease diagnosis and management and an awareness of the extent of variability in results from one laboratory to another, for example as described by Mitchell Lewis following his initial interlaboratory trials in the UK (1). The earliest EQA services were developed by committed and enthusiastic individual pathologists and laboratory scientists, often with limited resources and alongside their day-to-day clinical services ; at the time, it was thought that harmonisation of performance would be achieved by the operation of a short-term programme of inter-laboratory testing rounds. The aim of this Special issue of Biochemia Medica is to provide a comprehensive overview of the latest developments in EQA and keep our readers up-to-date with the role and significance of EQA in laboratory medicine and its future directions taking into account the changing demands of the profession and the evolution of analytical technology. In this issue we provide a number of outstanding contributions by internationally recognised experts in the field, who have been invited to address various issues and different aspects of EQA in the modern time, almost seven decades after its very origins.