Statistics for Method Verification of Quantitative Assays in Clinical Microbiology

Diagnostic information that describes the actual or relative density of specific microbes in human blood or in other clinical samples is possible because of quantitative molecular methods. Common methods include quantitative polymerase chain reaction (Q-PCR) or quantitative reverse transcription PCR (QRT-PCR). In clinical microbiology, the use of Q-PCR or QRT-PCR is commonly performed for the purpose of viral load testing, which supports the diagnosis, prognosis, therapeutic decisions, clinical strategies, and practices that monitor patients with blood-borne pathogen infections or infections due to organ transplants. For microbial load testing, standardizing results is challenging and evolving with the addition of more quantitative virus standards that support benchmarking of both FDA-cleared methods and laboratory-developed tests. Because there are unique verification requirements for deployment of quantitative molecular methods, this review focuses on the background and biostatistics required to assess the performance of quantitative molecular methods for determination of viral or microbial load testing in the clinical laboratory setting.