Last update:
29-Sep-2000

Arch Hellen Med, 17(1), January-February 2000, 77-88

APPLIED MEDICAL RESEARCH

Intralaboratory quality control
of hematological analyzers
by the use of control samples

V. PAPADOPOULOS,¹ A. AGORASTI^2
1Internal Medicine Unit,
²Hematology Laboratory, Xanthi General Perfecture Hospital, Xanthi, Greece

This article concerns the detection and measurement of errors and biases which characterize the counting of blood parameters during routine blood analysis carried out by automatic hematological analyzers, and the establishment of control and corrective intervention procedures by the use of control samples. Emphasis is placed on (a) explanation of the basic statistical principles used in intralaboratory control, (b) the exploitation of more elaborate (and thus more close to reality) mathematical models which can be applied to the quantitative measurement of errors and biases by the use of controls, and (c) the construction of charts which make these errors and biases easier to detect and thus to eradicate. The whole theoretical concept is encompassed in a numerical example along with the relevant charts. This aims to encourage the establishment of a similar procedure for hematological analyzers of other laboratories. An overall assessment of the present intralaboratory and interlaboratory quality control is attempted. Questions are raised and possible answers are proposed concerning each step of these procedures so as to ensure higher quality laboratory performance. Reliance is placed on the clarity and accuracy of the estimation of the so called total percent error of a chance measurement, which is the sum of the mean percent bias plus the mean percent error. The total percent error is the most widely used criterion for characterizing the quality of work of a hematological analyzer.

Key words: Control samples, Hematological analyzers, Intralaboratory quality control.