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A longitudinal replicate study of immunosuppressive drugs: a College of American Pathologists study
Bernard W Steele1, Edward Wang, Steven J Soldin
1Department of Pathology, University of Miami School of Medicine, Miami, FL, USA. bsteele;camed.miami.edu
Objective:
To identify the sources of analytical variation for cyclosporine and tacrolimus in a 3-year longitudinal study.
Design:
Two pools of whole blood were spiked with cyclosporine and tacrolimus, respectively. One aliquot of cyclosporine and 2 of the tacrolimus pool were distributed in the first and last mailing for years 1999 to 2001. For both drugs, the total variance for each method was partitioned into within- and between-laboratory components.
Setting:
The A and C mailings of the 1999, 2000, and 2001 AACC/CAP [American Association for Clinical Chemistry/College of American Pathologists] Immunosuppressive Drugs (CS) Monitoring Survey.
Main Outcome Measures:
For each drug, total variance was partitioned into specimen, mailing, year, and interlaboratory effects for each analytical method.
Participants:
The 292 laboratories for cyclosporine and 177 laboratories for tacrolimus enrolled in the survey from 1999 to 2001.
Results:
For both cyclosporine and tacrolimus, the major source of imprecision came from within-laboratory factors, which accounted for nearly 85% (range, 77% to 90%) of the total variance. For cyclosporine, the major component of within-laboratory variance was between-mailing, within-year effect, whereas for tacrolimus it was the between-year, within-laboratory variation.
Conclusion:
The major source of long-term survey imprecision for cyclosporine and tacrolimus is within-laboratory factors. The finding that 85% of the total variance was due to within-laboratory variation is similar to other therapeutic drugs.