Data from 2 years' operation of an External Quality Assessment Scheme covering 14 analytes and with some 60 participants is presented. Following the trimming of discrepant results and statistical ‘outliers' (outside the range of ±3 SD from the mean), there was generally close agreement between consensus mean values for a specimen analysed on different occasions, by different groups of laboratories, or when using different analytical methods. An improvement in performance, indicated by a reduction in the average inter-laboratory coefficient of variation was found for 11 of the 14 analytes over the 2-year period.
References
1.
BüttnerJBorthRBoutwellJHProvisional recommendations on quality control in clinical chemistry. Part 5. External quality control. Clin Chim Acta1978; 83: 191–202F.
2.
External quality assessment of health laboratories. Copenhagen: WHO Regional Office for Europe, 1981.
3.
WhiteheadTPBrowningDMGregoryA.A comparative survey of the results of analyses of blood serum in clinical chemistry laboratories in the United Kingdom. J Clin Pathol1973; 26: 435–45.
4.
WhiteheadTP. Quality Control in Clinical Chemistry. New York: Wiley, 1977.
5.
Guidelines of the Medical Society of West Germany for statistical quality control and collaborative surveys. Mitteilungen der Deutschen Gesellschaft für Klinishe Chemie1974; 3: 33–6.
6.
JansenAPVan KampenEJLeijnseBExperience in the Netherlands with an external quality control and scoring system for clinical chemistry laboratories. Clin Chim Acta1977; 74: 191–201.
7.
De LeenheerAPDe RuyterMGMSteyaertHLC. A method for the statistical evaluation of results in external quality control surveys. Clin Chim Acta1976; 71: 229–38.
8.
De LeenheerAPSteyaertHLCThienpontLMRJonckheereJA. External quality control of clinical chemistry laboratories in Belgium. Clin Chim Acta1983; 133: 1–14.
9.
StammD.A new concept for quality control of clinical laboratory investigations in the light of clinical requirements and based on reference method values. J Clin Chem Clin Biochem1982; 20: 817–24.
10.
HansenEStammD.Determination of assigned values in control specimens for internal accuracy control and for interlaboratory surveys. J Clin Chem Clin Biochem1980; 18: 461–90.
11.
WhiteheadTP. Advances in quality control. Adv Clin Chem1977; 19: 175–205.
12.
GilbertRK. A comparison of participant mean values of duplicate specimens in the CAP chemistry survey programme. Am J Clin Pathol1976; 66: 184–92.
13.
WhiteheadTPWoodfordFP. External quality assessment of clinical laboratories in the United Kingdom. J Clin Pathol1981; 34: 947–57.
14.
GilbertRK. Accuracy of clinical laboratories studied by comparison with definitive methods. Am J Clin Pathol1978; 70: 450–70.
15.
GeorgesRJWestonWC. Local experience with the use of WHO tentative reference serum for electrolytes. Clin Chem Newsletter1983; 3: 167–71.
16.
OlazabalDAVR. WHO tentative reference serum in clinical chemistry with values assigned for electrolytes by definitive methods. Clin Chem Newsletter1981; 1: 38–40.
