Accuracy of participant results utilized as target values in the CAP Chemistry Survey Program

Samples of lyophilized human serum were circulated to more than 7,000 participants in the College of American Pathologists chemistry survey program. The participants measured the concentrations of glucose, cholesterol, uric acid, and urea along with other constituents in the samples. Selected samples also were sent to the National Bureau of Standards (NBS) for analysis of these same analytes by definitive methods. Consensus mean values of participant results are used as target values. The participant values were compared with the NBS values, providing a measure of the accuracy of the designated target values. There was, in general, excellent correlation between the NBS definitive values and the designated target values. These target values can provide reliable reference points by which to evaluate participant performance.