Personal Assessment of Ability to Drive Under the Influence of Alcohol vs. Objective Measurement

Alcohol intoxication often affects patient management in the emergency department.

This study evaluates participants' subjective sense of impairment using ability to drive as a reference compared with measured breath alcohol concentrations (BrAC) and evaluate whether there is a gender difference.

In this prospective study, 55 volunteers consumed one beer and estimated their BrAC and their ability to drive. BrAC was measured objectively and participants were blinded to the value until they reached a BrAC of 0.1 g/dL. Then they stopped drinking and estimated their BrAC and ability to drive every 30 min until objective BrAC reached 0.08 g/dL.

As BrAC increased, the association between estimated and perceived ability to drive was significantly different (p < 0.0001). At BrAC levels > 0.08 g/dL, 20.3% affirmed the ability to drive. At BrAC levels < 0.08 g/dL, 35.5% denied ability to drive. As BrAC decreased, the association between estimated and actual ability to drive was significantly different (p = 0.001). At BrAC values > 0.08 g/dL, 59.7% affirmed the ability to drive. At BrAC < 0.08 g/dL, 49.1% denied ability to drive. As BrAC increased, the correlations for men and women were strong and statistically significant (r = 0.80, p < 0.0001 and r = 0.79, p < 0.0001, respectively). As men's and women's BrAC decreased, the women's correlation was higher (r = 0.061 and r = 0.74, respectively; p < 0.0001).

Both genders can estimate their impaired ability to drive while drinking, but women are better at assessing their capacity to drive after drinking cessation.