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PubMed · 10823379

Proficiency-testing issues relating to sirolimus.

K Jones·A Johnston·D W Holt
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Abstract

BACKGROUND: A need exists to document laboratory proficiency to (1) compare results produced by different analytical techniques and (2) ensure consistency of results from multiple testing sites. OBJECTIVES: To enable concentration-controlled studies of sirolimus to proceed with confidence, proficiency-testing schemes were put in place at laboratories selected to act as reference laboratories. The feasibility of establishing an ongoing proficiency-testing scheme was addressed with respect to sample stability. The scheme was then used to test proficiency for the measurement of sirolimus in 3 blinded samples each month. METHODS: The method chosen for measurement of sirolimus was a prototype microparticle enzyme immunoassay. Initially, 15 laboratories were asked to analyze a series of 85 blinded samples that tested their inaccuracy, repeatability, and reproducibility for the measurement and their ability to dilute over-range samples competently. Both blood samples spiked with sirolimus and pooled blood samples from patients receiving the drug were circulated to a maximum of 50 laboratories. RESULTS: Overall, both inaccuracy and imprecision were acceptable by predefined criteria. Inaccuracy for the immunoassay (percentage difference of the measured value against the nominal value) averaged -5% (95% CI, -9% to -1%). The mean percentage difference between the immunoassay and a high-performance liquid chromatographic assay with mass-spectrometric detection for the measurement of sirolimus in pooled samples (n = 5) from patients receiving the drug was 29% (95% CI, 24% to 34%). CONCLUSION: The techniques documented here as part of the International Sirolimus Proficiency Testing Scheme could be applied to other clinical studies requiring protocol-driven dosing adjustments based on sirolimus measurements, irrespective of analytical technique used.

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Chromatography, High Pressure LiquidHumansImmunoassayImmunosuppressive AgentsLaboratoriesPilot ProjectsReagent Kits, DiagnosticReproducibility of ResultsSirolimusSpectrophotometry, UltravioletTime FactorsJournal ArticleResearch Support, Non-U.S. Gov't

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K Jones, A Johnston, D W Holt. 2000. Proficiency-testing issues relating to sirolimus.. https://doi.org/10.1016/s0149-2918(00)89028-1

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