[Problems in practical implementation of the external quality control program in clinical laboratory investigations].

Center for External Quality Assessment in Laboratory Medicine has been organized in Russia. The National External Quality Assessment Scheme for 16 common analyses in clinical chemistry was implemented in 1992 under governmental support. A total of 1180 laboratories wished to participate in the program. 636 laboratories presented the results of analyses of 4 control serum pools, 2 with normal and 2 with increased concentrations of the constituents. Each control pool was analyzed twice allowing separate estimation of the accuracy and precision. Accuracy was assessed as the bias from method-dependent means and reference values. Reference methods were implemented for sodium, potassium, total protein, cholesterol, and triglycerides. Analysis of variance demonstrated that the errors are mainly due to the variability of methodologies in different laboratories, this variability being negligible.