User Verification of Performance for Precision and Trueness; Approved Guideline
|Publication Date:||1 April 2006|
This guideline was developed for situations where the performance of the method was previously established and documented by experimental protocols with large scope and duration. The experimental and statistical protocols of this guideline have relatively weak power to reject claims with statistical confidence, and should only be used to verify that the method is operating in accordance with the manufacturer's claims. This document is not intended to establish or validate the analytical performance of a method.
Since this document's scope is limited to verification of precision and trueness, other more rigorous CLSI/NCCLS protocols (e.g., EP6-Evaluation of the Linearity of Quantitative Measurement Procedures: A Statistical Approach; EP17-Protocols for Determination of Limits of Detection and Limited of Quantitation; and C28-How to Define and Determine Reference Intervals in the Clinical Laboratory) are employed to validate the method's performance against the user's needs. CLSI/NCCLS documents EP5-Evaluation of Precision Performance of Quantitative Measurement Methods and EP9-Method Comparison and Bias Estimation Using Patient Samples were developed to assist manufacturers in validating the performance of a diagnostic device for precision and trueness, respectively. CLSI/NCCLS document EP10-Preliminary Evaluation of Quantitative Clinical Laboratory Methods is intended for the rapid preliminary evaluation of precision, bias, sample carryover, drift, and nonlinearity. However, it is fairly complex since it is based on a multifactor design and is limited in the amount of data generated. EP10 should only be used as a preliminary evaluation of analytical performance.
One May also note that the EP15 protocol has an implicit assumption: namely, that if the estimated precision and trueness are acceptable, then the overall error (e.g., total analytical error) of the method is acceptable. This implied model can lead to an underestimation of the total analytical error in cases where other effects are important. Besides conducting more extensive evaluations mentioned above, one could also consider performing the CLSI/NCCLS protocol EP21-Estimation of Total Analytical Error for Clinical Laboratory Methods. This protocol is a direct estimation of total analytical error and does not rely on a model.