A study of the accuracy and precision of clinical chemistry determinations in 170 Canadian laboratories

Lyophilized samplesof two serum pools,prepared commercially, were sent to 200 Canadian clinical chemistry laboratories for estimations of total cholesterol, sodium, chloride, glucose, nonprotein or urea nitrogen, total protein, and inorganic phos-phorus. The purpose of this evaluation study was to determine if these laboratories, as a group, were performing satisfactorily, and to help individual laboratories to evalu-ate their performances and detect gross errors in their results. Values were reported from 170 laboratories. A summary of the complete data is presented in the form of tables, scatter diagrams, and frequency charts. It was found that there was a lack of accuracy and precision in many laboratories. Over 40 % of the 3762 values reported fell outside of the allowable limits of errors and therefore were classifiedas unacceptable. These results indicated a need for improved performances in many of the participating laboratories. S INCE 1947 a considerable number of evaluation studies of the ac-curacy of clinical chemistry determinations have been carried out in various countries (1-5). They have shown that there is a need for im-proved performance in many laboratories. Canadian experience has been gained from a number of surveys conducted by Tonks and Alie