Comparison of Bio-Rad %CDT TIA and CDTect as laboratory markers of heavy alcohol use and their relationships with gamma-glutamyltransferase

Background. Carbohydrate-deficient transferrin (CDT) is used as a serum mar ker for heavy drinking. We compared a new Bio-Rad %CDT TIA assay with the C DTect(TM)) assay; we also compared both to gamma -glutamyl-transferase (GGT ) as markers of heavy drinking. Methods: Serum samples of well-defined alcoholics (n = 404) and matched (ag e, race, and gender) social drinkers (204) from 10 clinical centers were as sayed with both CDT assays. Both assays use microcolumn separation after ir on saturation, followed by enzyme immunoassay (CDTect) or turbidimetric imm unoassay (Bio-Rad %CDT). In the latter, CDT is expressed as a percentage of total transferrin. Results: The slope and intercept [95% confidence intervals (Cls)] for linea r regression of results obtained by the %CDT-TIA (as percentage) and CDTect (units/L) assays were 0.091 (0.088-0.097) and 0.70% (0.54-0.86%), respecti vely (S-y/x =1.30%; r = 0.848). The areas under the ROC curves (95% Cls) fo r CDTect and Bio-Rad %CDT TIA were 0.89 (0.86-0.92) and 0.88 (0.85-0.91), r espectively, for men (P, not significant) and 0.76 (0.72-0.80) and 0.72 (0. 68-0.76) for women (P, not significant). When CDT (CDTect or Bio-Rad %CDT) was combined with GGT (either one positive), the clinical sensitivity in me n was 90% for both assays, and specificities were 81% and 84%, respectively , sensitivities in women were 75% and 76%, respectively, and specificities were 87% and 91%. Conclusion: The new Bio-Rad %CDT TIA assay compares favorably to the widely studied CDTect assay in the detection of alcohol-use disorders. (C) 2001 A merican Association for Clinical Chemistry.