Carbohydrate Deficient Transferrin (CDT) as a Biomarker to Assess Drinking in High - Risk Drink Drivers

The diagnostic value of biomarkers of alcohol consumption differs dependent upon the population under investigation. In this regard, clarification is needed in the choice of biomarker used to aid the medical assessor support a return to driving after a drink-driving offence. Blood samples were collected (5mL serum and 3.5mL whole blood EDTA) to measure carbohydrate deficient transferrin (%CDT) as a biomarker of alcohol consumption compared to gamma glutamyl transferase (GGT), mean corpuscular volume (MCV), aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Subjects were recruited to reflect the characteristics of a high-risk drink driving community in the United Kingdom. The ICD-10 or the Alcohol Use Disorders Identification Test (AUDIT) was used to diagnose an alcohol use disorder. 358 participants were recruited: 165 seeking treatment for harmful use or alcohol dependence: 142 seeking treatment for liver, diabetes or obesity problems: and 51 social drinkers (controls). %CDT was able to identify drinking indicative of excessive alcohol intake significantly more accurately than other biomarkers (Z=-9.017, p<0.001). The positive predictive value for %CDT (+ve PPV 0.88) demonstrated the best diagnostic power when tested compared to GGT (+ve PPV 0.69), inclusive of confounders. When the whole study population was taken into account the sensitivity and specificity of %CDT for the diagnosis of excessive alcohol use remained unchanged (area under curve 0.91) whereas the diagnostic power of GGT was poorer (area under curve 0.80). %CDT was superior to GGT as a marker of excessive alcohol consumption (continuous drinking) when tested against a population that included diabetic, obese and patients with non-alcoholic liver disease: a data set which bests mimics those seen in the high-risk drink driving population.