EP31-A-IR:2012

This document provides guidance on how to verify comparability of quantitative laboratory results for individual patients within a health care system. For the purpose of this document, a health care system is defined as a system of physician offices, clinics, hospitals, and reference laboratories, under one administrative entity, where a patient may present for laboratory testing, and whose results may be reviewed by any health care provider within the system for the purpose of providing medical care. EP31 provides a simple approach to be used for the assessment of patient laboratory result comparability across a maximum of 10 instruments, and assumes that a more comprehensive validation of quantitative measurement system comparability has been undertaken when the measurement systems were initially introduced into the laboratory. A more comprehensive comparison among measurement procedure results can follow a methodology such as that described in CLSI document EP09.1 Comparability testing is just one facet of a program for assuring quality laboratory performance and is not intended to be a substitute for other quality monitors. This document does not address corrective action should method noncomparability be identified. The approach described can also be used to verify comparability of patients’ results in situations such as those following reagent or calibrator lot changes, instrument component changes or maintenance procedures, alerts from QC or external quality assessment (EQA) (proficiency testing [PT]) events, or other special cause event.