Trueness verification in European external quality assessment schemes: time to care about the quality of the samples

REFERENCES

• Directive 98/79/EC of the European Parliament and of the Council of 27 October 1998 on in vitro diagnostic medical devices. Official J Eur Commun 1998; Dec 7: L 331/1—L 331/37.
   Google Scholar
• International Organization for Standardization (ISO), European Commission for Standardization (CEN). CEN prEN ISO 17511 (draft Dec 2000) IVD medical devices—measurement of quantities in samples of biological origin—metrological traceability of values assigned to calibrators and control materials (ISO/DIS 17511: 2000).
   Google Scholar
• European Committee for Standardization (CEN). prEN 14136:2001. Use of external quality assess-ment schemes in the assessment of the perfor-mance of in vitro diagnostic procedures. Brussels: CEN; 2001.
   Google Scholar
• Stöckl D, Reinauer H. Candidate reference methods for the determination of target values for cholesterol, creatinine, uric acid, and glucose in external quality assessment and internal accuracy control. I. Method setup. Clin Chem 1993; 39: 993–1000.
   Google Scholar
• Thienpont LM, De Leenheer AP, Stöckl D, Reinauer H. Candidate reference methods for the determination of target values for cholesterol, creatinine, uric acid, and glucose in external quality assessment and internal accuracy control. II. Method transfer. Clin Chem 1993; 39: 1001–6.
   Google Scholar
• Stöckl D, Franzini C, Kratochvila J, Middle J, Ricós C, Siekmann L, Thienpont LM. Analytical specifications of reference methods. Compilation and critical discussion (from the members of the European EQA-organizers Working Group B) [review]. Eur J Clin Chem Clin Biochem 1996; 34: 319–37.
   Google Scholar
• Thienpont LM, Franzini C, Kratochvila J, Middle J, Ricós C, Siekmann L, Stöckl D. Analytical quality specifications for reference methods and operating specifications for networks of reference laboratories. Discussion paper from the members of the external quality assessment (EQA) Working Group B on target values in EQAS. Eur J Clin Chem Clin Biochem 1995; 33: 949–57.
   Google Scholar
• Siekmann L. Reference methods for total choles-terol and total glycerol. Eur J Clin Chem Clin Biochem 1991; 29: 277–9.
   Google Scholar
• Schumann G, Böttner J. Determination of glucose in reference materials by isotope dilution—mass spectrometry. Fresenius Z Anal Chem 1988; 330: 424–5.
   Google Scholar
• Miller WG, Kaufman HW. College of American Pathologists Conference XXIII on matrix effects and accuracy assessment in clinical chemistry: introduction. Arch Pathol Lab Med 1993; 117: 343 —436.
   Google Scholar
• Miller WG, Levine JB, Santulli M, Flom KJ, Greenberg N, Kessner A, O'Neal WR, Wiebe DA, Adiletto C. Effect of freezing on cholesterol in individual sera. Clin Chem 1991; 37: 584–5.
   Google Scholar
• Waymack PP, Miller WG, Myers GL. Assay instrument-dependent matrix effects in standardi-zation of cholesterol measurements. Clin Chem 1993; 39: 2058–62.
   Google Scholar
• Stöckl D, Libeer J-C, Reinauer H, Thienpont LM, De Leenheer AP. Accuracy-based assessment of proficiency testing results using serum from single donations: possibilities and limitations. Clin Chem 1996; 42: 469–70.
   Google Scholar
• Linko S, Himberg J-J, Thienpont LM, Stöckl D, De Leenheer AP. Assessment of the state-of-the-art trueness and precision of serum total-calcium and glucose measurements in Finnish labora-tories—The QSL-Finland study. Scand J Clin Lab Invest 1998; 58: 229–40.
   Google Scholar
• Ross JW, Miller WG, Myers GL, Praestgaard J. The accuracy of laboratory measurements in clinical chemistry: a study of 11 routine chemistry analytes in the College of American Pathologists Chemistry Survey with fresh frozen serum, defini-tive methods, and reference methods. Arch Pathol Lab Med 1998; 122: 587–608.
   PubMed Web of Science ®Google Scholar
• Baadenhuijsen H, Demacker PN, Hessels M, Boerma GJ, Penders TJ, Weykamp C, Willems HL. Testing the accuracy of total cholesterol assays in an external quality-control program. Effect of adding sucrose to lyophilized control sera compared with use of fresh or frozen sera. Clin Chem 1995; 41: 724— 30.
   Google Scholar
• Ross JW, Myers GL, Gilmore BF, Cooper GR, Naito HR, Eckfeldt J. Matrix effects and the accuracy of cholesterol analysis. Arch Pathol Lab Med 1993; 117: 393–400.
   Google Scholar
• Naito HK, Kwak YS, Hartfiel JL, Park JK, Travers EM, Myers GL, Ross JW, Eckfeldt JH, Hartmann AE. Matrix effects on proficiency testing materials. Impact on accuracy of choles-terol measurement in laboratories in the nation's largest hospital system. Arch Pathol Lab Med 1993; 117: 345–51.
   Google Scholar
• Myers GL, Waymack PP. Matrix effects in biological reference materials used in the standar-dization of cholesterol measurements. Fresenius J Anal Chem 1990; 338: 538–42.
   Google Scholar
• Libeer J-C, Baadenhuijsen H, Fraser CG, Hyltoft Petersen P, Ricós C, Stöckl D, Thienpont LM. Characterization and classification of external quality assessment schemes (EQA) according to objectives such as evaluation of method and participant bias and standard deviation. Eur J Clin Chem Clin Biochem 1996; 34: 665–78.
   Google Scholar
• Eckfeldt JH, Copeland KR. Accuracy verification and identification of matrix effects. Arch Pathol Lab Med 1993; 117: 381–6.
   Google Scholar
• International Organization for Standardization (ISO), Clinical laboratory medicine—requirements for reference measurement laboratories. ISO/DIS 15195. Geneva: ISO, draft 2000.
   Google Scholar