Usefulness of indirect alcohol biomarkers for predicting recidivism of drunk-driving among previously convicted drunk-driving offenders: results from the Recidivism Of Alcohol-impaired Driving (ROAD) study

Aim: In several European countries, drivers under the influence (DUI), suspected of chronic alcohol abuse are referred for medical and psychological examination. This study (the ROAD study, or Recidivism Of Alcohol-impaired Driving) investigated the usefulness of indirect alcohol biomarkers for predicting drunk-driving recidivism in previously convicted drunk-driving offenders.Design, setting, participants and measurements: The ROAD study is a prospective study (2009-13) that was performed on 517 randomly selected drivers in Belgium. They were convicted for drunk-driving for which their licence was confiscated. The initial post-arrest blood samples were collected and analysed for percentage carbohydrate-deficient transferrin (%CDT), transaminsase activities [alanine amino transferase (ALT), aspartate amino transferase (AST)], gamma-glutamyltransferase (GT) and red cell mean corpuscular volume (MCV). The observation time for each driver was 3 years and dynamic.Findings: A logistic regression analysis revealed that ln(%CDT) (P<0.001), ln(GT) (P<0.01) and ln(ALT) (P<0.05) were the best biochemical predictors of recidivism of drunk-driving. The ROAD index (which includes ln(%CDT), ln(GT), -ln(ALT) and the sex of the driver) was calculated and had a significantly higher area under the receiver operator characteristic curve (0.71) than the individual biomarkers for drunk-driving recidivism. Drivers with a high risk of recidivating (ROAD index25%; third tertile) could be distinguished from drivers with an intermediate risk (16%ROAD index<25%; second tertile; P<0.001) and a low recidivism risk (ROAD index<16%; first tertile;P<0.05).Conclusions: Of all routinely used indirect alcohol markers, percentage of carbohydrate-deficient transferrin is the major predictor of recidivism of drunk-driving. The association with gamma-glutamyltransferase, alanine amino transferase and the sex of the driver could have additional value for identifying drunk-drivers at intermediate risk of recidivism. Non-specific indirect alcohol markers, such as alanine amino transferase, gamma-glutamyltransferase, aspartate amino transferase and red cell mean corpuscular volume have minimal added value to % carbohydrate-deficient transferrin for distinguishing drunk drivers with a low or high risk of recidivism.