Reference ranges
Reference ranges were established independently at each institution using samples from 20 to 110 normal individuals, or were verified using samples from at least 20 individuals according to the protocols described in CLSI EP28-A3 [8]. There were ten tests sets with less than 20 samples due to infrequent order. All individuals were presumptively normal and the samples were de-identified prior to use. All studies were conducted in compliance with each institution's IRB policies.
Compilation of data from all three institutions
WF and NMH contributed data from one AU5822 analyzer each; IU contributed data from two analyzers (IU1 and IU2). The precision and linearity/AMR data were tabulated. For the method comparison studies, the data from each institution were analyzed separately and then combined for additional analysis with the exception of lactate which was only analyzed separately for 2 institutions. Supplemental Table 4 showed the correlation and bias plots. The Deming regression line for the combined data was calculated and plotted along with the 95% confidence limits.
Results and discussion
Data were available for 84 analytes at IU, 58 analytes at NMH, and 87 analytes at WF. Of these, complete data sets that included precision, linearity/AMR, method comparison and reference ranges were available from one or more institutions for 66 analytes. For these 66 analytes being studied as a group, the specimen types included serum/plasma for 53 analytes, urine for 12 analytes and CSF for 1 analyte, totalling 12,064. Of the 53 analytes using serum/plasma, 40 were chemistries and the remaining 13 were drugs used for therapeutic drug monitoring (TDM). For this paper we focused on those 66 analytes evaluated for all elements of the study, i.e., precision, linearity/AMR, method comparison, and reference range at one or more of the institutions. At each site the individual data were examined to ensure results were within acceptable limits for that institution.
Precision
Data from precision studies conducted at each of the three institutions were collated to evaluate the combined precision at multiple analyte levels for the QC materials tested. Each precision set includes 20 data points. The precision data set for 66 analytes is available online as Supplemental Table 1 measured assay precision.