Cas Weykamp1, Jos Wielders2, Anders Helander3, Raymond F Anton4, Vincenza Bianchi5, Jan-Olof Jeppsson6, Carla Siebelder7, John B Whitfield8, François Schellenberg9. 1. Department of Clinical Chemistry, Queen Beatrix Hospital, Winterswijk, the Netherlands; c.w.weykamp@skbwinterswijk.nl. 2. Department of Clinical Chemistry, Meander Medical Center, Amersfoort, the Netherlands; 3. Department of Laboratory Medicine, Karolinska Institutet, and Karolinska University Laboratory, Clinical Chemistry, Stockholm, Sweden; 4. The Center for Drug and Alcohol Programs, Medical University of South Carolina, Charleston, SC; 5. Toxicology Reference Laboratory, SS. Antonio e Biagio Hospital, Alessandria, Italy; 6. Department of Laboratory Medicine, Malmö University Hospital, Malmö, Sweden; 7. Department of Clinical Chemistry, Queen Beatrix Hospital, Winterswijk, the Netherlands; 8. Queensland Institute of Medical Research, Brisbane, Australia; 9. Laboratoire de Biochimie, Hôpital Trousseau, Tours, France.
Abstract
BACKGROUND: The need for equivalent results of routine measurement procedures for the alcohol biomarker carbohydrate-deficient transferrin (CDT) has been recognized by the IFCC. This article describes a project to harmonize CDT as conducted by an IFCC working group initiated for this purpose. METHODS: We used procedures for achieving harmonization as developed by the Consortium for Harmonization of Clinical Laboratory Results to assess the suitability of a candidate reference measurement procedure (cRMP), candidate reference materials (cRMs), and the success of efforts to achieve harmonization. RESULTS: CDT measurement procedures in routine use showed good reproducibility (CV 1.1%-2.8%) and linearity (r > 0.990) with variable slopes (0.766-1.065) and intercepts (-0.34 to 0.92) compared to the cRMP. Heterogeneity after simulated harmonization was 4.7%. cRMs of frozen human native sera demonstrated commutability and 3-year stability for routine measurement procedures. The cRMP provided reproducible value assignment to cRMs with an expanded uncertainty (k = 2) of 0.03% at the 1.2% CDT level and 0.06% at the 4.4% CDT level. Harmonization efforts reduced the intermeasurement CV from 8.8% to 3.4%, allowed 99% recovery of the values assigned with the cRMP, and demonstrated 99% of results within the desirable allowable total error. Harmonization was less successful in samples with low CDT and high trisialotransferrin concentrations. CONCLUSIONS: Harmonization of CDT is possible with frozen human native sera as cRMs with values assigned by use of the cRMP. We propose the cRMP as a candidate international conventional reference measurement procedure and cRMs as candidate international calibrators.
BACKGROUND: The need for equivalent results of routine measurement procedures for the alcohol biomarker carbohydrate-deficient transferrin (CDT) has been recognized by the IFCC. This article describes a project to harmonize CDT as conducted by an IFCC working group initiated for this purpose. METHODS: We used procedures for achieving harmonization as developed by the Consortium for Harmonization of Clinical Laboratory Results to assess the suitability of a candidate reference measurement procedure (cRMP), candidate reference materials (cRMs), and the success of efforts to achieve harmonization. RESULTS: CDT measurement procedures in routine use showed good reproducibility (CV 1.1%-2.8%) and linearity (r > 0.990) with variable slopes (0.766-1.065) and intercepts (-0.34 to 0.92) compared to the cRMP. Heterogeneity after simulated harmonization was 4.7%. cRMs of frozen human native sera demonstrated commutability and 3-year stability for routine measurement procedures. The cRMP provided reproducible value assignment to cRMs with an expanded uncertainty (k = 2) of 0.03% at the 1.2% CDT level and 0.06% at the 4.4% CDT level. Harmonization efforts reduced the intermeasurement CV from 8.8% to 3.4%, allowed 99% recovery of the values assigned with the cRMP, and demonstrated 99% of results within the desirable allowable total error. Harmonization was less successful in samples with low CDT and high trisialotransferrin concentrations. CONCLUSIONS: Harmonization of CDT is possible with frozen human native sera as cRMs with values assigned by use of the cRMP. We propose the cRMP as a candidate international conventional reference measurement procedure and cRMs as candidate international calibrators.