Intermethod Variation in Serum Carcinoembryonic Antigen (CEA) Measurement. Fresh Serum Pools and Control Materials Compared

Abstract

This study was undertaken to evaluate the feasibility of using commercial control materials in a regional external quality assessment scheme (EQAS) for serum carcinoembryonic antigen (CEA) measurement. We have assessed the commutability of 12 commercial control materials using five automated immunochemical systems. We compared the intermethod behavior of the materials with that of 12-14 patient serum pools. In a total of 48 comparisons (12 materials x 4 pairs of analytical systems), seven instances of non-commutability were apparent, as shown by normalized residuals falling outside the +/-3 interval. The use of non-commutable materials generates two negative effects. In EQAS, the interlaboratory variation recorded is not representative of the variation expected in the assay of patient sera; in interlaboratory harmonization programs, recalibration with non-commutable materials increases, instead of decreasing, the interlaboratory variation. Both these effects were shown to occur in CEA measurement with the tested materials and systems. The materials planned to be used in our EQAS turned out to be commutable: this gave us the guarantee of measuring realistic interlaboratory variation values, although the check for commutability should be extended to all the analytical systems used by the participants in the scheme.

AACC Creatine Kinase MB (CK-MB) Standardization Material Used as Manufacturer’s Working Calibrator Is Unable to Harmonize CK-MB Results between Two Commercial Immunoassays

“…9, 2004 samples in the evaluated assays. Two recently published studies showed the perverse effect of recalibrating immunoassays measuring cardiac or tumor markers with noncommutable materials and the consequent misinterpretation of patient results (11,12 ). As demonstrated previously for another proposed CK-MB reference material (13 ), our results show that the AACC CK-MB standardization material cannot be used to directly calibrate commercial assays without rigorous verification of its commutability among procedures.…”

Longitudinal Evaluation of AFP and CEA External Proficiency Testing Reveals Need for Method Harmonization

“…Investigations are needed to determine whether and how much influence the spiking has on the EQA results. Nevertheless, manufacturer-dependent differences could also be observed within patient samples by several other researchers [10,11,15,16], so our observed manufacturer-specific results are most likely not caused by the spiked material alone. Other EQA providers also used spiked sample materials [12,33] and especially Sturgeon et al deemed that a lack of commutability was unlikely due to the minimal manipulation of the sample material [19].…”

“…The glycoproteins AFP and CEA have long been approved as biomarkers, with International Reference Preparations (IRPs) having been available since 1975 [ 9 ]. Even though these reference standards have been around for decades, multiple studies have reported method- or manufacturer-dependent differences for both markers [ 10 , 11 , 12 , 13 , 14 , 15 ]. The Society for Promoting Quality Assurance in Medical Laboratories (INSTAND) is a German, non-profit interdisciplinary scientific medical society.…”

Imprecision of tumour biomarker measurements on Roche Modular E170 platform fulfills desirable goals derived from biological variation

“…lyophilized samples) than with native patient samples. 5,6 Annals of Clinical Biochemistry 2010; 47: 171-173…”

“…lyophilized samples) than with native patient samples. 5,6…”