Concurrent validity of an Estimator of Weekly Alcohol Consumption (EWAC) based on the Extended AUDIT
Software repository for:
Dutey-Magni, P. (2020). '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 commonly employed in healthcare to screen for levels of alcohol consumption. AUDIT-C scores (0–12) have no direct interpretation and do not provide information on alcohol intake, an important variable for behaviour change. The study aimed to (a) develop a continuous metric from the Extended AUDIT-C, offering equivalent accuracy, and providing a direct estimator of weekly alcohol consumption (EWAC); (b) evaluate the EWAC's bias and error using the Graduated-Frequency (GF) questionnaire as a reference standard of alcohol consumption.
Design: Diagnostic evaluation using cross-sectional data from 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) Extended AUDIT and (b) GF. The primary outcomes were: mean deviation <1 UK unit (metric of bias); root mean squared deviation <2 UK units (metric of total error) between EWAC and GF. The secondary outcome was an equivalent Receiver Operating Characteristics’ area under the curve for predicting alcohol consumption in excess of 14 and 35 UK units compared to AUDIT-C and AUDIT.
Findings: EWAC had a positive bias of 0.2 UK units [95% confidence interval: 0.04, 0.3] compared to GF. Deviations were skewed: while the mean error was ±11 UK units/week [9.8, 12.0], in half of participants the deviation between EWAC and GF was between 0 and ±2.1 UK units/week. EWAC predicted consumption in excess of 14 UK units/week with a significantly greater area under the curve (0.921 [0.917, 0.925]) than AUDIT-C (0.871 [0.866, 0.876]) or the full AUDIT (0.854 [0.849, 0.860]).
Conclusions: The EWAC https://ewac.netlify.app is designed to estimate weekly alcohol consumption using answers to the Extended AUDIT-C questionnaire. Using the detailed GF as a reference standard, the EWAC met the targeted bias tolerance. Its accuracy was superior to that of both AUDIT-C and the full AUDIT in relation to consumption thresholds, making it a reliable complement to the Extended AUDIT-C for health promotion interventions.