Search

Background: ISO 15189: 2003 was developed in order to establish requirements for the Accreditation of Clinical Laboratory Quality Management System and Technical Competition, including standards from the pre to post examination stages. From the medical point of view the most important issue of the new norm, is the need to generate medically relevant results, making necessary for the laboratory professionals to watch for the reliability of the studies, and to become more involved on the suitable indication and utilization of the tests, and to be aware on the correct interpretation and better use of the results. Objective: To review ISO 15189: 2003 and to document the medical relevance concept and the issues that may derive from the human perspective and from the technological dimension. Material and methods: This is a revision article on which the analytical process in its three stages is evaluated. Practical definitions, formulas and examples are presented as indicators of medical relevance that can be applied on the internal and external quality control programs. Results: The basic utility of the tests of the laboratory depends fundamentally on their medical relevance, which can as be evaluated on an objective form in the internal quality programs and in the external proficiency schemes. Discussion: Medical relevance depends from the start on the decision to use the clinical laboratory tests, depending on what test is to be performed, who indicates it, why and what for is carried out, who process it and where is developed, who controls it and finally what is done with the results. When the tests are carried out under suitable conditions, in a laboratory with well established quality control programs in which objective indicators are applied, it turns out feasible to evaluate the relevance of the results through the simultaneous measurement of the biological variability and analytical variability according to the described method on this communication. [ABSTRACT FROM AUTHOR]

Background: SIX SIGMA appeared in the industry in 1979 in order to obtain quality improvement manufacture processes to a level of 3.4 defects per million units (DPMU). It involves all the system from agreed goals establishment with customer's requirements, to statistical data measurement, team work, and continuous quality improvement. Objective: To briefly review and document SIX SIGMA principles and tools in order to evaluate its applicability on the clinical laboratory, including the importance of comparing the impact of SIX SIGMA level with pre-established analytical goals according to the analytical coefficient of variation of Tonks and Aspen that have been used in clinical laboratories for decades as precision indicators. Material and methods: This is a revision of the basic concepts and the fundamental methods of SIX SIGMA, including definitions, formulas and practical exercises and examples on the indicators of analytical variability based on pre-established reference limits and ranks of biological variability for the analytical control of quality according to Tonks, Aspen and SIX SIGMA criteria, emphasizing the applicability of the relative coefficient of variation CVR as practical tool for analytical goal management on any laboratory test. Results: The criterion of Tonks is equivalent to 25.0% of the normal rank representing a biological standard deviation. The Aspen criterion is equivalent to 50% of Tonks level representing 12.5% of the normal rank. In order to reach SIX SIGMA level it is necessary to improve Tonks level precision in six times, which implies to reduce the analytical variability to 4.2% of biological variability. In order to evaluate the relation that exists between biological variability (BV) and the analytical variability (AV) it is recommended to calculate quotient AV / BV which will give a result of < 1.0 according to Tonks, < 0.50 according to Aspen and <0.17 when SIX SIGMA level is reached. Discussion: The establishment of attainable and challenging analytical goals is the first step in any quality control system. The relative coefficient of variation calculation allows laboratories a reliable and easy approach on analytical goal establishment for any analyte with the only condition of having suitable reference limits for the attended population and the calculation of the analytical coefficient of variation for the specific test. The advance in quality improvement depends on the establishment of the actual level in which the laboratory is at the present moment. In order to improve quality it is necessary to improve good laboratory practices and to elevate the automation level of the laboratory. The achievement of analytical goals will be different depending on the level in which they are applied in such a way that the results that are obtained in the Internal Program of Control of Quality should be better than those than are reached on External Evaluation Quality Schemes, because for statistical reasons the confidence intervals vary inversely depending on the number of variables that take part in the process. [ABSTRACT FROM AUTHOR]

Background: ISO 15189 «Quality Management in the Medical Laboratory» has been developed for clinical laboratories evaluation, quality improvement and accreditation. This standard involves analytical process completely, from pre to post examination stage, giving importance to biological and analytical variability in addition to methodological traceability, test validation and the measurement of uncertainty and medical relevance. Objective: To clearly and briefly review and document uncertainty biostatistical principles that are applicable to the clinical laboratory including standard error, relative coefficient of variation, standard deviation index and total error as fundamental indicators of quality control. Material and methods: This is a review article of the scientific literature in which definitions, formulas and practical exercises on uncertainty indicators and total variability in analytical control of quality are documented. Results: It is clearly demonstrated that the utility of laboratory tests depend on multiple factors, which must be known, supervised and controlled as far as possible through analytical process. Discussion: The utility of these concepts depends on the routine application of quality indicators, which at the present time is highly feasible, since personal computers are already common tools in almost every clinical laboratory worldwide. Daily estimation of these formulas is actually quite simple leading to a dramatic positive impact on quality improvement of laboratory data when knowledge can be applied in order to control uncertainty. [ABSTRACT FROM AUTHOR]