scope:

This guideline explains the purpose of statistical QC for quantitative measurement procedures, describes an approach for planning a QC strategy for a particular measurement procedure, describes the use of QC material and QC data, and provides examples that demonstrate a practical QC planning process for medical laboratories.

The recommendations for establishing and maintaining a statistical QC strategy are applicable to quantitative laboratory measurement procedures in all fields of laboratory medicine for which stable control materials can be measured in the same manner as patient specimens. The intended users of this guideline include those responsible for designing, implementing, and using QC, ie, medical laboratory scientists.

This guideline does not:

• Describe built-in control mechanisms that might be part of a measuring system, or qualitative or semiquantitative measurement procedures.
• Define specific QC strategies that are appropriate for an individual device or technology.
• Describe alternatives to statistical process control, eg, real-time patient-based QC.
• Consider specific legal requirements that may impose different philosophies or procedures on QC practices (eg, a specific approach for defining quality requirements, specific values for quality requirements, a specific procedure for determining target values for control materials, or a frequency and number of QC measurements) defined by government regulation in a specific country or region.

Additionally, there are types of random errors that may affect measurements performed on individual specimens, rather than a whole group of specimens, and those errors are not detected by a statistical QC strategy. Such errors may be due to the specific design of a measuring system (eg, effect of specimen viscosity, carryover from a previous specimen, or specimen-specific interferences) or possible operator errors that affect individual specimens, as well as preexamination errors of specimen preparation, storage, and transportation. Special QC strategies may be needed to monitor known special vulnerabilities that relate to a particular device or system design.