Quality control in clinical chemistry

Whitehead TP (1976) Quality Control in Clinical Chemistry. Wiley, Chichester,... 

Ingamells CO, PiTARD FF (1986) Applied Geochemical Analysis, pp L-84.Wiley, New York. International Federation of Clinical Chemistry (IFCC) (1978) Expert Panel on Nomenclature and Principles of Quality Control in Clinical Chemistry. Clin Chim Acta 83 L89F-202F. International Organization for Standardization (ISO) (1993) Guide to the expression of uncertainty. Geneva. 

Westgard jo, Barry PL, Hunt MR (1981) A multi-rule Shewhart chart for quality control in clinical chemistry. Clin Chem 27 493-501. 

A reference method is one which after exhaustive investigation has been shown to have negligible inaccuracy in comparison with its imprecision [International Federation of Clinical Chemistry (IFCC), 1979]. With its comparison of inaccuracy and imprecision this definition clearly refers to the principles of quality control in clinical chemistry. Indeed, statistical models such as Youden plots are used to find out whether the error in a pair of results happens by chance (imprecision of the method) or is systematic (inaccuracy) (Youden, 1967). If the results are close to the true values, inaccuracy is negligible in comparison with imprecision. As demonstrated earlier, each analytical procedure has a certain degree of imprecision consequently, the total absence of systematic error can never be proved. Only as the influence of a systematic error is evident in comparison with the influence of chance or random error can the systematic error be demonstrated. 

IFCC (1976). Internationa] Federation of Clinical Chemistry. Committee on standards expert panel on nomenclature and principles of quality control in clinical chemistry. Provisional recommendations on quality control in clinical chemistry, Part 1 General principles and technolgoy. Clin. Chem. 22, 532-540. 

Figure 19-14 Westgard multirule control chart having control limits drawn at the mean s, 2s, and 3s. Concentration is plotted on the y-axis versus time (run number) on the x-axis. A, Chart for high-concentration control material. B, Chart for low-concentration control material. (From Westgard JO, Barry Pi, Hunt MR, Groth T.A multhrule Sbewhart chart for quality control in clinical chemistry. Clin Chem 1981 27 493-501.)...

Buttner J, Borth R, BoutweH JH, et al. International Federation of Clinical Chemistry provisional recommendation on quality control in clinical chemistry I. General principles and terminology. CHn Chem 1976 22 532-9. 

In 1961 Braunsberg and James (B17) gave an exhaustive account of the statistical evaluation of methods for estimating adrenocortical steroids and pointed out that very few published methods up to that time had been evaluated in a manner which would pass muster by the orthodox criteria of general analytical chemistry. In this, however, the steroid field is not much worse than other areas of analytical biochemistry, and it is only relatively recently that a serious move to improve precision and quality control in clinical chemistry has gained acceptance. An excellent general review is given by Whitby et al. (W3). In this section I shall cover only certain points which seem to be specifically important in steroid work. 

J. O. Westgard, P. L. Barry, and M. R. Hunt, A Multi-Rule Shewhart Chart for Quality Control in Clinical Chemistry, Clin. Chem., 27 (1981) 493. 

BCittner, J., Borth, R., Boutwell, J.H. and Broughton, P.M.G. (1976). Provisional recommendation on quality control in clinical chemistry. Clin. Chem., 22, 532. 

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