scope:

This guideline describes a statistically sound protocol for evaluating the consistency of patient sample results when a new analytical reagent lot replaces a reagent lot currently in use. It is designed for use with quantitative measurement procedures, and more generally for measurement procedures that report on a continuous scale. The same principles can be applied to measurement procedures that convert results from a continuous scale to a qualitative report based on a cutoff value. This guideline is intended for use in the medical laboratory and is designed to work within the practical limitations of that environment.

This guideline is not intended for use with measurement procedures that provide only qualitative or semiquantitative results. It is also not intended for measurement procedures for which a shift in patient results is expected with new reagent lots. For some measurement procedures, a shift in patient results with a new reagent lot is usual and expected, because the reagents are biological materials that may have lot-to-lot differences. Such measurement procedures include prothrombin time and activated partial thromboplastin time. The usual processes for clinical use of these measurement procedures account for this expected difference, and new lot evaluation as described in this guideline is not necessary or useful. Guidance for these measurement procedures provides detail on handling reagent lot changes. See CLSI documents H47¹ and H54.²

Additionally, this guideline is not intended to describe procedures for reagent manufacturers. The requirements of reagent lot-to-lot testing by manufacturers, as well as the resources available, are different from those of the medical laboratory. However, reagent manufacturers may use this guideline to understand the types of verification studies that may be performed in their customers' laboratories.