scope:

The purpose of this document is to help clinical laboratories use proficiency testing (PT) as a quality improvement tool. 15-20 This guideline delineates a systematic approach to monitoring PT results, and to investigating and responding to unacceptable PT results, including a classification of the types of problems that cause PT failures. This document also provides guidance for how to use PT as a tool to prevent problems through analysis of acceptable results, education of laboratory personnel, and monitoring of internal process.

This guideline is applicable to any setting in which clinical laboratory testing is performed, from bedside testing to large multispecialty laboratories. Laboratories may use a similar approach to monitor and investigate unacceptable results from internal quality control programs, as well as "split sample" quality control programs. Please refer to the most current editions of CLSI document C24-Statistical Quality Control for Quantitative Measurement Procedures: Principles and Definitions for additional guidance for quality control applications, and CLSI/NCCLS document GP29-Assessment of Laboratory Test When Proficiency Testing Is Not Available.

This guideline applies to both qualitative and quantitative laboratory testing, including detection and quantification of blood and fluid analytes, morphologic identification, and blood and tissue typing. Some of the discussions apply only to tests with quantitative results, whereas other discussions apply to tests with qualitative results.

The processes in this guideline can help laboratories prepare responses to regulatory and accrediting bodies. The processes include impact assessment, root cause analysis, and corrective action. However, laboratories are cautioned that oversight bodies may have additional requirements not covered in this document, and they may have differing interpretations of the requirements.

This document is intended for laboratories, but also could be used by oversight bodies and PT providers as guidance for reporting and interpreting performance. In addition to providing processes for tracking laboratory performance, this document includes guidance for other reviews of performance of different methods, such as reproducibility and bias, which should be performed by the providers of PT and by laboratory oversight bodies

This guideline does not prescribe specific corrective or preventive actions that are appropriate for their specific root causes. The document applies to PT programs that test laboratory results, and does not apply to the use of PT for assessing the competence of individual analysts.a