Factors Associated with Self-Estimated Breath Alcohol Concentration Among Bar Patrons

Alcohol Clin Exp Res. 2017 Aug;41(8):1492-1501. doi: 10.1111/acer.13428. Epub 2017 Jul 6.


Background: Few studies have examined the context in which drinkers underestimate their breath alcohol concentration (BrAC) in natural drinking environments. This study examined factors associated with bar patrons' self-estimated BrAC in high-risk college town settings.

Methods: Guided interview and BrAC data were collected from 510 participants recruited as they exited bars located close to large universities: 1 in Florida and 1 in Texas.

Results: Participants with the highest measured BrACs underestimated their BrAC levels the most. Findings from multivariable linear regression analysis indicated that BrAC (std β = 0.014, p < 0.001), number of alcoholic drinks consumed (std β = 0.006, p < 0.01), and perceived drunkenness (std β = 0.024, p < 0.001) had significant positive associations with BrAC self-estimates, where the regression coefficients were scaled by values approximately equal to each variable's interquartile range. Among the 321 participants with BrAC levels ≥ 0.08 g/dl, 21.2% believed their BrAC was below the legal per se driving limit of 0.08 g/dl. Results from a logistic regression analysis indicated that higher levels of perceived drunkenness were associated with better self-recognition that one's BrAC level exceeded the legal driving threshold (OR = 3.312, p < 0.001). Further, participants under 26 years of age had reduced odds of recognizing that their BrAC was greater than 0.079 g/dl (OR = 0.245, p < 0.05).

Conclusions: These findings highlight the inaccuracy of self-estimated BrAC when drinking, particularly among younger drinkers. Adjusting for BrAC, situational factors were strongly associated with self-estimated BrAC. Future research is needed to better understand how altering drinking environments may improve accuracy of BrAC self-estimates and deter driving after drinking.

Keywords: Errors in Self-Estimation of Breath Alcohol Concentration; Inaccuracy of Perceived Blood Alcohol Concentration Levels; Misperceptions of BAC Self-Estimates.

MeSH terms

  • Adult
  • Alcohol Drinking / epidemiology
  • Alcohol Drinking / psychology*
  • Alcoholic Beverages*
  • Alcoholic Intoxication / diagnosis
  • Alcoholic Intoxication / epidemiology
  • Alcoholic Intoxication / psychology*
  • Breath Tests / methods
  • Female
  • Humans
  • Male
  • Retrospective Studies
  • Self Concept*
  • Students / psychology
  • Surveys and Questionnaires / standards*
  • Young Adult