The diagnostic power of direct carbohydrate-deficient transferrin immunoassay in alcoholics. Absolute or relative values?

The objective of this study was to compare the diagnostic power of direct carbohydrate-deficient transferrin (CDT) immunoassay in alcohol abuse expressed in relative units with the diagnostic power of the results expressed in absolute units. Serum CDT was determined in 127 alcoholics using N Latex CDT direct immunonephelometric assay (Siemens Healthcare Diagnostics, Marburg, Germany). The diagnostic sensitivity, specificity, negative and positive predictive value, and also the positive and negative likelihood ratios do not differ between results expressed in relative or absolute units independently of cutoff chosen. Finally, the area under the receiver operating characteristic (ROC) curves for N Latex CDT test expressed in absolute units does not differ from the area for results expressed in relative units. We conclude that the diagnostic usefulness of N Latex immunonephelometric assay using the relative or absolute values is the same.