Concurrent validity of an Estimator of Weekly Alcohol Consumption (EWAC) based on the Extended AUDIT

Background and Aims: The 3-question Alcohol Use Disorders Identification Test (AUDIT-C) is frequently used in healthcare for screening and brief advice about levels of alcohol consumption. AUDIT-C scores (0–12) provide feedback as categories of risk rather than estimates of actual alcohol intake, an important metric for behaviour change. The study aimed to (a) develop a continuous metric from the Extended AUDIT-C expressed in United Kingdom (UK) units (8g pure ethanol), offering equivalent accuracy, and providing a direct estimator of weekly alcohol consumption (EWAC) and (b) evaluate the EWAC’s bias and error using the Graduated-Frequency (GF) questionnaire as a reference standard of alcohol consumption. Design: Cross-sectional diagnostic study based on a nationally-representative survey. Settings: Community-dwelling households in England. Participants: 22,404 household residents aged 16 years reporting drinking alcohol at least occasionally. Measurements: Computer-assisted personal interviews consisting of (a) AUDIT questionnaire with extended response items (the ‘Extended AUDIT’) and (b) GF. Primary outcomes were: mean deviation <1 UK unit (metric of bias); root mean squared deviation