Sensitivity and specificity of a commercial urinary ethyl glucuronide (ETG) test in heavy drinkers

INTRODUCTION: To advance the use of alcohol metabolites as biomarkers in the context of alcohol research, the present study tested the sensitivity and specificity of a commercially available urinary ethyl glucuronide (uEtG) test (DrugConfirm Advanced 80hr EtG) in a clinical research context. METHODS: A community sample of heavy drinkers (N = 68) completed the 30-day Timeline Follow-Back (TLFB) interview and provided a urine sample for uEtG analysis. Analyses of sensitivity and specificity of the uEtG assay were conducted using the following outcomes: (a) past day drinking, (b) past day binge drinking (defined as ≥4 drinks for women and ≥5 drinks for men), (c) past 3-day drinking, and (d) past 3-day binge drinking. RESULTS: The majority of participants reported past-3-day drinking (80.9%) and a sizeable minority reported past day drinking (33.8%). While uEtG-based detection of past day drinking and binge drinking was acceptable (sensitivity = 73.91%, and 83.33%; specificity = 80.00% and 66.13%, respectively), detection of any drinking and binge drinking in the past 3 days was poor (sensitivity and specificity of 43.64% and 84.62%, and 39.39% and 62.86%, respectively). CONCLUSIONS: This study contributes to the mixed findings on the validity of EtG tests, which suggest that commercial uEtG tests with conservative detection thresholds are not a reliable alcohol biomarker without corroborating self-report data. Lower detection thresholds are recommended when using uEtG as an alcohol biomarker. Efforts to reach acceptable levels of sensitivity and specificity with commercial assays hold potential to advance the measurement of alcohol intake, overcoming the pitfalls of self-report data.