Analytical verification and validation of immunohistochemical tests and their equipment are common practice for today’s anatomic pathology laboratories. Few references or guidelines are available on how this should be performed. The study of Sciensano (the Belgian national competent authority regarding licensing of medical laboratories) performed in 2016, demonstrated a significant inter laboratory variation in validation procedures of immunohistochemical tests among Belgian laboratories. These results suggests the unavailability of practical information upon the approach to verification and validation of these tests. The existing Belgian Practice Guideline for implementation of a quality management system in anatomic pathology laboratories has been reviewed to meet this demand and additionally to prepare the laboratories for the EU - IVD revised regulations (IVDR).

This paper describes Belgian recommendations for verification and validation of immunohistochemical tests prior to implementation, for ongoing validation and for revalidation. For each type of test (according to the IVDR classification and the origin) and its intended use (purpose), it addresses how to perform analytical verification/validation by recommending: (i) the number of cases in the validation set, (ii) the performance characteristics to be evaluated, (iii) the objective acceptance criteria, (iv) the evaluation method for the obtained results and (v) how and when to revalidate. A literature study and a risk analysis taking into account the majority of variables regarding verification/validation of methods have been performed, resulting in an expert consensus recommendation that is a compromise between achievability, affordability and patient safety. This new consensus recommendation has been incorporated in the aforementioned ISO15189:2012 based Practice Guideline.