Evaluation of two biological markers combined as a parameter of alcohol dependency.

A test was constructed by combining carbohydrate-deficient transferrin (%CDT) and gamma-glutamyltransferase (GT) and was evaluated in detecting alcohol-dependent patients in a surgical ward. The performance of the combined test was significantly better than that of either %CDT alone or GT alone, as evaluated by calculating sensitivity and likelihood ratio at a specificity of 0.85 and by comparing areas under receiver-operating characteristic curves statistically. Improved performance was found for the whole group of patients, for men, for patients older than 35 years of age, and for those patients consuming more than 60 g alcohol per day. The performance of %CDT alone was similar to that of GT, %CDT being better in the age group 35-50 years, whereas GT was better for those drinking less than 60 g per day and for the oldest patients (> 50 years). Neither of the two tests or their combination performed well for patients younger than 36 years of age.