One U.S. study found that 3.6% of those who were BAC positive at ER arrival denied any drinking within the six hours prior to the event while 29% of those who reported drinking during this time were negative for BAC (Cherpitel, 1989b). A similar study among injured patients found proportions denying drinking but registering positive for BAC ranging from 3.3% in Mexico, to 1.5% in Spain and .5% in the U.S., while proportions reporting drinking but registering negative for BAC were considerably greater (41% in the U.S., 37% in Spain and 18% in Mexico) (Cherpitel et al., 1992). To explore whether the validity of self-report was positively affected by patient’s being breathalyzed prior to eliciting a report (bogus pipeline effect), one ER study obtained self-report data prior to breathalyzing the patient on part of the sample, and following, on the remainder of the sample, with no effects in self-report validity observed (Cherpitel, 1993).
