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All you wanted to know about laboratory tests, but were afraid to ask. The informed patient meeting the laboratory director. Analytical Performance Goals. By Dietmar Stöckl ST T Consulting - 9 -. Today. The start. First general limits
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All you wanted to know about laboratory tests, but were afraid to ask The informed patient meeting the laboratory director Analytical Performance Goals By Dietmar Stöckl STT Consulting - 9 -
Today All you wanted to know about laboratory tests -9-
The start • First general limits • Belk W, Sunderman FW. A survey of the accuracy of chemical analyses in clinical laboratories. Am J Clin Pathol 1947;17:853-61 (reprinted in: Arch Pathol Lab Med 1988;112:320-6). • First goals based on biology • Tonks DB. A study of the accuracy and precision of clinical chemistry determinations in 170 Canadian laboratories. Clin Chem 1963;9:217-33. • % maximum total error (TEmax) • = 100 * [¼ of the reference interval (RI)/mean of RI] • “If the normal range for sodium is taken to be 135-145 mEq./L., then the allowable limits of error calculated by this formula are ± 1.8%”. • “The maximum limits for any determination, however, were set at ± 10%, even though in some cases those calculated by the above formula exceeded this figure”. All you wanted to know about laboratory tests -9-
The concepts • The discipline agreed on the hierarchy of models for establishing analytical performance goals# • Clinical concepts • Questionnaires to clinicians • Concepts based on biological variation • Expert opinion/Regulations • "State-of-the-art" • #Kenny D, Fraser CG, Hyltoft Petersen P, Kallner A. Strategies to set global quality specifications in laboratory medicine, Stockholm, 24-26 April 1999. Consensus agreement. Scand J Clin Lab Invest 1999;59:585. All you wanted to know about laboratory tests -9-
The reality • Clinical concepts & questionnaires to clinicians • Few data available • Concepts based on biological variation • Start getting used by industry; misconception: values are for the laboratory, industry should use more stringent goals • Expert opinion/Regulations • Highly variable • "State-of-the-art“ • Difficult to assess; information typically restricted to imprecision (www.westgard.com; several essays on “Sigma analysis”) All you wanted to know about laboratory tests -9-
The reality • Typically, there is no consensus between (and often within) the different concepts • TEa ofserum sodium measurement All you wanted to know about laboratory tests -9-
Resources • Educational material • >www.stt-consulting.com • >Education • General • >Analytical quality II • TSH example • >Analytical performance goals TSH • Performance goals from biology • www.westgard.com/biodatabase1.htm All you wanted to know about laboratory tests -9-
I type ... ... more needs to be done. A lot to think about All you wanted to know about laboratory tests -9-
The next visit Performance assessment See you next time. All you wanted to know about laboratory tests -9-