The CAP’s evidence-based guideline, "Principles of Analytic Validation of Immunohistochemical Assays," serves as a practical guide to help ensure accuracy and reduce variation in laboratory practices for immunohistochemical (IHC) test results for all patient specimens.
Recent studies confirmed the need to provide laboratories with consistent procedures to follow when validating IHC assays. The new guideline outlines 14 evidence-based and expert consensus recommendations that help ensure that an IHC test accurately measures the analyte of interest and that validation is appropriate for the test's intended use. Recommendations are also provided for verifying that an existing validated assay continues to perform as expected when there has been a change in laboratory location, test methods, or equipment. The guideline may also provide a framework for validating molecular and genomic-based assays.
The panel addressed the key question of "What is needed for initial analytic assay validation before placing any immunohistochemical test into clinical service and what are the revalidation requirements?" They conducted a systematic review of more than 125 publications covering almost 1,500 citations in the context of open comment feedback, quality of evidence, and their own expert judgments in the field of immunohistochemistry. The Pathology and Laboratory Quality Center provided the forum for the guideline development. The guideline will be updated as new scientific evidence becomes available.