Background There is a need for valid and reliable data on alcohol use in patients presenting to the Emergency Department (ED) to provide a more complete picture of the risk factors and inform targeted public health interventions and surveillance.

Aims This research aimed to test the ethical and practical processes required to conduct a prevalence study of alcohol consumption using a novel approach by using blood samples collected during routine care in ED presentations with two biomarkers, blood ethanol and phosphatidylethanol (PEth).

Methods This prevalence study involved the secondary use of routinely collected blood samples from patients presenting to the Royal Brisbane and Women’s Hospital ED. Samples were tested for acute and medium-term alcohol intake using ethanol and PEth, over one collection period of 10 days. Ethanol is a biomarker of recent acute alcohol consumption, whereas PEth is biomarker for alcohol exposure during the previous 2–4 weeks.

Results A total of 1,160 blood samples were intercepted and stored, between 22 January and 1 February 2021, including the Australia Day long weekend. The overall prevalence for blood ethanol was 9.3% (95%CI 7.8%-11.1%) in the total cohort, 5.3% for general medical presentations, increasing four-fold to 22.2% for injury presentations. The prevalence of PEth positive samples in the total cohort was 32.5% (95%CI 29.9%-35.3%), and 41.4% for injury presentations. There were 263 (25.3%) cases that tested negative for blood ethanol but positive for PEth concentrations indicative of significant to heavy alcohol use.

Conclusion This novel surveillance approach demonstrates that using blood ethanol tests in isolation significantly underestimates the prevalence of medium-term alcohol consumption in ED presentations. Performing periodic objective measurement of both acute and medium-term alcohol consumption accurately and objectively in ED presentations, would be valuable for informing targeted public health prevention and control strategies.