Proficiency test for rabies serology: A design complying with international standards for a reliable assessment of participating laboratories.

Background: Domestic carnivores can introduce rabies into disease-free countries or areas if they are incubating the disease and transported during the pre-symptomatic period. For pets moved into the European Union, the European Commission decided to establish a system of community approval of laboratories willing to carry out the rabies serological controls to guarantee an effective control system. As the specific institute to coordinate the approval of the laboratories, designated by the European Commission in 2000, our laboratory organizes annual proficiency tests (PT) for laboratories already agreed or willing to be agreed to perform rabies serological controls (by detecting rabies virus neutralizing antibodies only) in the frame of international trade. Methodology/Principal findings: The assessment criteria of this PT rely on the analysis of the specificity and the intra-laboratory consistency. The approach used to evaluate the degree of laboratory consistency is based on the use of compiled data obtained from previous PT campaigns, and is measured by the quality of a regression model. By using historical data for calculating assigned values and associated standard deviations, instead of values obtained from only one campaign, they became robust without any additional statistical treatment. In the present paper, more than 800 historical values were compiled for each of the regression parameters. Conclusions/Significance: Since the beginning of these PT schemes in 1999, the overall percentage of failing laboratories remained stable over the years (4.1%) while the number of participants increased to 79 in 2018. This highlighted the robustness and the consistency of the statistical analyses used to assess the laboratory's performance over the years. The improvements carried out and the consistency of our statistical analyses have resulted in the compliance of the rabies serology PT with the ISO/IEC 17043 and ISO 13528:2015 International Standards. Author summary: Proficiency testing (PT) schemes also known as "external quality assessment schemes" are one means to assess the quality and validity of routine measurements. PT schemes are the most common, and perhaps the most important type of inter-laboratory comparisons. As the specific institute to coordinate the approval of the laboratories, designated by the European Commission in 2000, our laboratory organizes annual PT for laboratories already agreed or willing to be agreed to perform rabies serological controls in the frame of international trade. Our PT program is conducted in compliance with the requirements of the ISO/ IEC 17043 International Standards. To enhance the robustness of our statistical analyses, we used an original approach to assess the performance of participants consisting in comparing individual laboratory values with assigned values calculated from compiled PT historical data. Since the beginning of these PT schemes in 1999, the overall percentage of failing laboratories remained stable over the years. The improvements carried out and the consistency of our statistical analyses have resulted in the compliance of the rabies serology PT with the International Standards. [ABSTRACT FROM AUTHOR]