An interlaboratory comparison of analyses of clinical specimens.

A pilot study was conducted to identify some of the benefits and limitations of making interlaboratory comparisons of clinical assays. Sixteen laboratories that participated in a regional quality control program and used similar instrumentation each provided analyses of specimens from three male and three female healthy subjects, 25 male and 25 female clinical subjects, and several control specimens. Analysis of the data revealed that the derived normal ranges agreed well with those provided by the instrument manufacturer, and that for some analytes the laboratories produced comparable clinical assays. The control specimens were found to be indicators of the presence of analytic bias that affected the clinical assays, but they did not always correctly indicate the kind or magnitude of bias. Using pattern recognition technics, it was shown that a laboratory's clinical assays had characteristic distributions that were apparently related to the populations served, as well as to analytic precision. The results demonstrate that useful information may be gleaned from interlaboratory surveys of clinical assays.