What's New in Laboratory Statistical Quality Control Guidance? The 4th Edition of CLSI C24, Statistical Quality Control for Quantitative Measurement Procedures: Principles and Definitions

In laboratory medicine, our main goal is to improve patient health by providing laboratory results that support medical decisions. To meet this goal, the laboratory needs to report accurate results that enhance care and minimize patient risk. Analytical goal setting helps the laboratory assure that when their measurement procedures are operating in their stable, in-control state, the patient results they report will be fit for their intended use. The laboratory's QC plan is designed to assure that even when test system failures occur, the risk of patient harm due to erroneous reported results is kept to acceptable levels. The CLSI C24 document first published as an approved guideline in 1991 has been a popular and useful resource to help laboratories design, implement, and assess their QC practices. The 4th edition of CLSI C24 titled Statistical Quality Control for Quantitative Measurement Procedures: Principles and Definitions has just been completed (1). As chair of the C24, 4th edition, document development committee, my goal, as I expressed it to the committee at our first meeting, was to keep the content that was still applicable and relevant to the modern laboratory, modify or enhance content where necessary to bring it in line with current laboratory thinking and practice, and add content related to those laboratory and health care issues that have risen in importance since the publication of the 3rd edition of the document in 2006. The result of the committee's work has produced a 4th edition that is approximately twice the size of the 3rd edition. This overview will briefly highlight some of the changes and additions included in the 4th edition. The publication in 2011 of CLSI EP23, Laboratory Quality Control Based on Risk Management, marked a change in perspective regarding the purpose and goals of laboratory QC (2). Many of the changes in the 4th edition of the C24 document were initiated to align it more closely with the concepts and principles espoused in EP23. The EP23 document describes a riskmanagement approach to laboratory QC that seeks to identify all possible failure modes in the laboratory, rank the identified failure modes in terms of their risk, and then establish policies and procedures to prevent or reduce the risks to acceptable levels. Risk is defined as the combination of the probability of occurrence of patient harm and the severity of the harm.