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All you wanted to know about laboratory tests, but were afraid to ask

All you wanted to know about laboratory tests, but were afraid to ask. The informed patient meeting the laboratory director. Assessment of Analytical Performance. By Dietmar Stöckl ST T Consulting - 10 -. The analytical quality triangle. For "valid" measurements…. Method evaluation/

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All you wanted to know about laboratory tests, but were afraid to ask

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  1. All you wanted to know about laboratory tests, but were afraid to ask The informed patient meeting the laboratory director Assessment of Analytical Performance By Dietmar Stöckl STT Consulting - 10 -

  2. The analytical quality triangle • For "valid" measurements… Method evaluation/ comparison Clinical Biology Expert Chemistry State-of-art Instrument Quality creation Quality specification Quality management Planning Control … the analytical quality triangle! Assurance Improvement All you wanted to know about laboratory tests -10-

  3. Performance characteristics • Precision (-profile) – Random error (RE) • Imprecision • Limit of detection (LOD) • Working range • Trueness/traceability – Systematic error (SE) • Calibration • Linearity (also may define Working range) • Recovery • Interferences • Specificity • Stability (shift & drift) • Carryover • Accuracy/result-traceability – Total error (TE) • Combination of precision and trueness • Ruggedness (robustness) • Correlation/comparison with other methods All you wanted to know about laboratory tests -10-

  4. Assessment of performance • Requirements • Standards (specifications, claims) for acceptable performance • Experimental protocols to estimate performance reliably ("Error assessment") • Criteria for comparing estimated performance with performance standards • Note: Apply a clinical perspective to the whole task!$Carey RN, Garber CC, Koch DD. Concepts and practices in the evaluation of laboratory methods. Workshop, AACC 48th Annual Meeting, Chicago (IL), July 28, 1996. All you wanted to know about laboratory tests -10-

  5. Standards • Analytical performance goals • The best “state-of-the-art” All you wanted to know about laboratory tests -10-

  6. Experimental protocols • CLSI protocols, for example • EP 5 Imprecision • EP 6 Linearity • EP 7 Interference • EP 9 Method comparison • EP 10 Preliminary evaluation • EP 12 Qualitative tests • EP 14 Matrix effects • EP 15 User demonstration precison & accuracy • EP 17 Limit of detection • EP 21 Total error All you wanted to know about laboratory tests -10-

  7. Selected experiments All you wanted to know about laboratory tests -10-

  8. Decision making • Modern interpretation of analytical data • Confidence intervals/statistical significance testing. • Statistical • Statistical tests versus Nul-hypothesis (F-test, t-test, 95% confidence-intervals, …): Bias = 0; Slope = 1; Intercept = 0; etc. • Analytical • Statistical tests versus estimates of stable performance (F-test, t-test, 95% confidence-intervals, etc.): Bias  calibration tolerance; etc. • Clinical • Statistical tests versus clinical limits (F-test, t-test, 95% confidence-intervals, etc.): REexp  REmax; SEexp  SEmax; TEexp  TEmax • In all three situations, we apply the same type of statistical tests: important is the test value All you wanted to know about laboratory tests -10-

  9. Decision making – Old vs modern All you wanted to know about laboratory tests -10-

  10. Resources • Westgard products • www.westgard.com • EP protocols • www.clsi.org • Educational material • www.stt-consulting.com • Laboratory statistics • www.medcalc.be • www.cbstat.com • www.analyse-it.com • www.dgrhoads.com/ • www.stt-consulting.com All you wanted to know about laboratory tests -10-

  11. I type ... Assessment of analytical quality … Do it the modern way. All you wanted to know about laboratory tests -10-

  12. Closure of the series Thanks for your patience! You really earned your credits All you wanted to know about laboratory tests -10-

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