Carbohydrate-deficient transferrin (CDT) has become widely used in traffic medicine to detect chronic alcohol abuse among subjects applying for driving-license renewal or regranting. By defining cut-off values in a large population of abstainers and moderate drinkers, we report on CDT, GGT–CDT (a combination of gamma-glutamylaminotransferase (GGT) and CDT) and the association between blood alcohol concentration (BAC) and CDT among Italian drivers.
A common CDT cut-off (1.8%) and gender-specific GGT–CDT cut-off (4.15% for males, 3.56% for females) were calculated as 99.9th percentiles of the control population. Also, 3% and 27% of subjects were classified as CDT positive respectively among drivers applying for license regranting and drivers involved in car accidents. A significant association between BAC and both CDT values and CDT positivity was found, with a frequency up to 49% of CDT samples, suggesting chronic alcohol abuse, among drivers with BAC >2.5g/l. Concordance between CDT and GGT–CDT was only moderate (kappa = 0.44), with CDT performing better than GGT–CDT.
A relevant proportion of drivers with high BAC are chronic abusers. GGT–CDT, previously validated with CDT immunoassays, should not be applied to traffic medicine in its current form and its performances re-evaluated with CDT measured by HPLC.
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