title: Comparison of CEDIA FK506 assay with HPLC/MS/MS in a large cohort of pediatric patients.
abstract: FK506 (tacrolimus), a macrolide immunosuppressant, is widely used in pediatric transplant patients, but a relatively narrow therapeutic window in children vs adults requires close and accurate monitoring of whole blood FK506 levels. High-pressure liquid chromatography/tandem mass spectrometry (HPLC/MS/MS)-based assays have been viewed as the gold standard but are more time and labor intensive than cloned enzyme donor immunoassay (CEDIA). To analyze differences between the 2 assays, we assayed FK506 in 348 split samples simultaneously by both methods. A further 70 samples were stratified by organ transplantation type: cardiac (13%), renal (23%), small bowel (22%), or liver transplantation (42%). Results were analyzed using standard statistical techniques for method comparison. CEDIA overestimated the FK506 value relative to HPLC/MS/MS by more than 20% in 40% of cases (139/348), whereas CEDIA underestimated the FK506 value relative to HPLC/MS/MS by more than 20% in 13.5% of cases, for a total inaccuracy of 53% using a ±20% cutoff. Only 28% of samples (99/348) measured by CEDIA were within 10% of the value obtained by HPLC/MS/MS. Bland-Altman analysis showed a mean bias of 9.5% in favor of CEDIA over HPLC/MS/MS (95% confidence interval, 6.1%-12.9%). Positive bias was greatest for liver transplant and R(2) values were lowest for intestinal transplant patients, indicating that HPLC/MS/MS may be a better option for this pediatric transplant subgroup.
authors.affiliation: University of Pittsburgh, Presbyterian Hospital–Shadyside, Pittsburgh, PA, USA.
authors.forename: Darla R
authors.initials: DR
authors.lastname: Lower
authors.forename: Lorna
authors.initials: L
authors.lastname: Cropcho
authors.forename: Adam
authors.initials: A
authors.lastname: Rosendorff
mesh_terms: D000293:Adolescent; D002648:Child; D002851:Chromatography, High Pressure Liquid; D016027:Heart Transplantation; D006801:Humans; D007124:Immunoenzyme Techniques; D007166:Immunosuppressive Agents / Q000097:blood*; D007421:Intestine, Small / Q000637:transplantation; D016030:Kidney Transplantation; D016031:Liver Transplantation; D016559:Tacrolimus / Q000097:blood*; D053719:Tandem Mass Spectrometry
chemical_list: D007166:Immunosuppressive Agents; D016559:Tacrolimus
keywords: CEDIA; FK506; Method comparison; Tacrolimus; Transplantation