Originally posted April 21st, 2006
Those who will influence the future quality of laboratory testing
CLSI Area Committee on Evaluation Protocols
CLSI Subcommittee on Establishment of Manufacturer’s QC Recommendations
CLSI Subcommitee on Laboratory Quality Control Procedures
I want to call your attention to an article on “The Quality of Laboratory Testing Today” that was published in the American Journal of Clinical Pathology in March 2006 (v125:pp343-354). This article was prepared for the “QC for the Future” workshop, which was held in March 2005 in Baltimore. Because you attended this conference and/or are involved in the ongoing project work to develop QC for the Future, I hope you will have some interest in the results of this study.
I take the unusual step of calling your attention to this study to ensure that the CLSI committees charged with the responsibility for future QC practices are challenged to consider the current analytical quality of laboratory tests in quantitative and measurable terms. Emerging laboratory quality indicators, such as being proposed by IQLM, focus mainly on pre-analytic and post-analytic variables and pay little attention to analytical quality. The results of this study indicate that the analytical quality of laboratory tests is still a serious problem that requires ongoing improvements in analytical methodology and laboratory QC.
In considering QC for the Future, CLSI seems to be driven by the ISO guideline for manufacturers (ISO 15198: Validation of manufacturer’s recommended procedures for quality control) which recommends a risk analysis approach to identify sources of variability that ideally should be eliminated by careful design of the analytic system. In Section 4 on “Quality control recommendations,” the following guidance is given to manufacturers:
Section 4.1: “Residual risks should be minimized by the manufacturers’ recommended quality control procedures. The quality control procedures shall include a method of detection (e.g., quality control material, electronic monitoring system, or on-board chemical control) and acceptability criteria that will determine when a critical failure occurs or a means to determine the acceptability criteria. Limitations of the quality control procedure shall be identified and described in the instructions for use.”
While that guidance is fine and good for manufacturers, I want to remind you of ISO 15189 document (Medical laboratories – Particular requirements for quality and competence), which provides guidance to laboratories. In discussing examination procedures (i.e., measurement procedures), laboratories are given the following specific guidance:
Section 5.5.4: “Performance specifications for each procedure used in an examination shall relate to the intended use of that procedure.”
Section 5.6.1: “The laboratory shall design internal quality control systems that verify the attainment of the intended quality of results.”
Note first the need to define the “intended use” or “intended quality” in order to implement examination procedures with appropriate precisian and accuracy, as well as the appropriate QC design.
Note first the need to define the “intended use” or “intended quality” in order to implement examination procedures with appropriate precision and accuracy, as well as the appropriate QC design. Second, the guidance for internal QC design doesn’t say mitigate or reduce or minimize the risk of not attaining the intended quality of results - it says to verify the attainment of the intended quality of results. The laboratory is responsible for verifying that the intended quality is achieved, not just minimizing the risk of poor quality.
This objective of verifying the attainment of intended quality of results can be achieved by designing a statistical QC procedure to account for the quality required for the test and the precision and accuracy observed for the measurement procedure, as described in CLSI document C24-A3 (Statistical Quality Control for Quantitative Measurement Procedures: Principles and Definitions). Note that the ISO guidance to manufacturers identifies statistical QC as an example “method of detection,” thus statistical QC is an appropriate way to monitor residual risks, as well as to verify the attainment of the intended quality of test results.
As you develop recommendations for QC for the Future, please keep in mind that statistical QC is still a valuable tool to verify the attainment of the intended quality of test results. There seems to be a predisposition today to try to avoid the application of statistical QC in laboratories, or reduce the amount of QC performed, as evidenced by the original CMS proposal for “equivalent QC procedures.” It is important to set the objective as performing the right amount of QC to detect medically important errors, which depend on the quality required for the test and the precision and accuracy observed for the measurement procedure. In any approach you recommend, make sure you can account for intended quality and verify its attainment in routine laboratory operations. Otherwise, we run the risk that the quality of laboratory testing in the future will be worse than it is today.
Reference: Westgard JO, Westgard SA. The Quality of Laboratory Testing Today: An assessment of Sigma metrics for analytic quality using performance data from proficiency testing surveys and the CLIA criteria for acceptable performance. Am J Clin Pathol 2006;125:343-354.
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