Intermethod variation in serum carcinoembryonic antigen (CEA) measurement. fresh serum pools and control materials compared.
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.
Dominici
Roberto
R
Istituto di Scienze Biomediche Ospedale L. Sacco, Università degli Studi di Milano, Italy.
Cabrini
Enrico
E
Cattozzo
Giampaolo
G
Ceriotti
Ferruccio
F
Grazioli
Vittorio
V
Scapellato
Luisa
L
Franzini
Carlo
C
D002138:Calibration; D002272:Carcinoembryonic Antigen / Q000097:blood*; D006801:Humans; D012015:Reference Standards; D015203:Reproducibility of Results
D002272:Carcinoembryonic Antigen