title: The relationship between self-reported drinking and BAC level in emergency room injury cases: is it a straight line?
abstract: BACKGROUND
  While the validity of self-reported consumption based on blood alcohol concentration (BAC) has been found to be high in emergency room (ER) samples, little research exists on the estimated number of drinks consumed given a BAC level. Such data would be useful in establishing a dose-response relationship between drinking and risk (e.g., of injury) in those studies for which the number of drinks consumed is not available but BAC is.
  
  
  METHODS
  Several methods were used to estimate the number of drinks consumed in the 6 hours prior to injury based on BAC obtained at the time of ER admission of n = 1,953 patients who self-reported any drinking 6 hours prior to their injury and who arrived to the ER within 6 hours of the event, from the merged Emergency Room Collaborative Alcohol Analysis Project (ERCAAP) and the World Health Organization Collaborative Study on Alcohol and Injury across 16 countries.
  
  
  RESULTS
  The relationship between self-reported consumption and averaged BAC within each consumption level appeared to be fairly linear up to about 7 drinks and a BAC of approximately 100 mg/dl. Above about 7 reported drinks, BAC appeared to have no relationship with drinking, possibly representing longer consumption periods than only the 6 hours before injury for those reporting higher quantities consumed. Both the volume estimate from the bivariate BAC to self-report relationship as well as from a Widmark calculation using BAC and time from last drink to arrival to the ER indicated a somewhat weak relationship to actual number of self-reported drinks.
  
  
  CONCLUSIONS
  Future studies may benefit from investigating the factors suspected to be driving the weak relationships between these measures, including the actual time over which the reported alcohol was consumed and pattern of drinking over the consumption period.
authors.affiliation: Alcohol Research Group, Emeryville, California 94608, USA. jbond@arg.org
authors.forename: Jason
authors.initials: J
authors.lastname: Bond
authors.forename: Yu
authors.initials: Y
authors.lastname: Ye
authors.forename: Cheryl J
authors.initials: CJ
authors.lastname: Cherpitel
authors.forename: Robin
authors.initials: R
authors.lastname: Room
authors.forename: Jürgen
authors.initials: J
authors.lastname: Rehm
authors.forename: Guilherme
authors.initials: G
authors.lastname: Borges
authors.forename: Mariana
authors.initials: M
authors.lastname: Cremonte
authors.forename: Gerhard
authors.initials: G
authors.lastname: Gmel
authors.forename: Wei
authors.initials: W
authors.lastname: Hao
authors.forename: Hana
authors.initials: H
authors.lastname: Sovinova
authors.forename: Tim
authors.initials: T
authors.lastname: Stockwell
mesh_terms: D000428:Alcohol Drinking / Q000097:blood*; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D000431:Ethanol / Q000097:blood*; D006801:Humans; D015203:Reproducibility of Results; D012307:Risk Factors; D012650:Self Disclosure; D014944:World Health Organization; D014947:Wounds and Injuries / Q000453:epidemiology*
chemical_list: D000431:Ethanol