Validity of self-reports of drinking before injury by cause of injury and societal context among emergency department patients.

Validity of self-report compared to breathalyzer readings at the time of admission to the ED was high, but varied by cause of injury, BAC level, country-level detrimental drinking patterns and the restrictiveness of alcohol control policy. Findings may support the utility or self-reports as an alternative to a quantifiable measure of BAC in the ED setting.