Ensuring PCR Quality – Quality Criteria and Quality Assurance

Abstract

When quality issues are discussed in any manufacturing or result-orientated process, then two key terms are often quoted, namely "quality control" and "quality assur-ance". These two terms are often used interchangeably, but in fact refer to two different procedures. Quality control refers to a system of routine and consistent controls, which help ensure data integrity, data correctness and data completeness. Moreover, quality control helps identify and correct any errors or omissions that have occurred during processing, as well as recording and archiving processing results and quality control data. On the other hand, quality assurance involves a planned system of review procedures, preferably performed by an independent "third party" laboratory, which monitors quality control procedures and verifies that quality objectives have been (and are being) met. Over the past few years, PCR applications and protocols have been developed, optimized, and implemented, for use within a wide range of clinical disciplines. As with the development of any "in house" assay whose results influence clinical decision making, quality criteria for these new PCR protocols have had to be developed in order to comply with both good laboratory practice (GLP) and (inter)national guidelines. Quality criteria for "classical" diagnostic tests such as culture-based assays and ELISAs have already been defined and parallel guidelines for quality controlling, as well as quality assuring, novel PCR-based assays are under continuous development and refinement. Efficiency, sensitivity, specificity, accuracy and reproducibility are all extremely important factors with regard to the official acceptance of novel PCR assays within the clinical diagnostic laboratory, especially now that PCR-based techniques are increasingly being used as diagnostic tools and affecting patient treatment regimens. It should be noted however, that not all PCR assays have to comply with strict clinically oriented quality guidelines, a fact often true in relation to PCR assays used within "research-only" environments. This means that the decision over which PCR assays should be strictly quality controlled depends on the use to be made of the results, which ultimately lies in the hands of the laboratory scientists using that particular PCR assay. Some common concepts and terms used in assessing the quality criteria of newly developed or newly implemented PCR assays within the clinical diagnostic laboratory are presented below. For a more detailed discussion, the reader is referred to two particular reviews [Niesters, 2002; Neumaier et al., 1998]. E. Van Pelt-Verkuil et al., Principles and Technical Aspects of PCR Amplification, 213