Assuring analytical quality through process planning and quality control.

United States governmental regulations describe quality assurance as a system in which quality control (QC) and proficiency testing are to be used to substantiate that routine tests conform to specified performance criteria. Careful planning of analytical processes is necessary to guarantee that routine tests will achieve the analytical performance defined by the Health Care Financing Administration proficiency testing criteria. These proficiency testing criteria are analytical "total error" requirements that need to be translated into operational process specifications for the allowable imprecision, allowable inaccuracy, and the QC procedure (decision rules, number of control measurements) necessary to provide a known or specified level of analytical quality assurance. The level of assurance will depend on the QC procedure's probability for detecting critical sized errors that would cause the quality requirement to be exceeded. Analytical quality can be guaranteed by applying statistical QC to verify, with a specified probability, that a desired quality requirement is actually achieved in routine laboratory testing. Analytical quality assurance, applied in this way, can be a quantitative approach for guaranteeing quality through process planning and QC.