Statistics for Method Verification of Qualitative Assays in Clinical Microbiology

Evaluation of analytical performance of qualitative and semi-quantitative assays in the clinical laboratory

As is true for quantitative assays, qualitative and semi-quantitative assays, producing strict binary or ordinal results, must undergo a verification process prior to their implementation for routine clinical laboratory testing. Standard method validation parameters used for quantitative assays, however, do not apply here. Rather, contingency tables, Bayesian statistics and statistical hypothesis testing for inter-rater agreement must be used. This article provides an overview of simple, practical tools, which can be used to verify the analytical performance of such assays. Topics discussed include the verification of precision and accuracy with a single experiment approach and performing method comparison experiments for assays with binary or ordinal results. Acceptance criteria are recommended for each test to provide a standardized framework for performance assessment. The approach is appropriate for all CE/IVD-marked and CLIA-waived assays and will ensure compliance with CAP, ISO 17025 and ISO 15189 regulations.