Influence of age, gender, and blood-alcohol concentration on the disappearance rate of alcohol from blood in drinking drivers.

The rate of disappearance of alcohol from the blood (beta-slope) was determined in drinking drivers by taking two blood samples about 60 min apart (mean 68 min, span 30 to 120 min). The results were compared for men and women as a function of their age and the prevailing blood-alcohol concentration (BAC). The material consisted of 1090 double blood samples from 976 men and 114 women with mean age 36.6 +/- 12.9 y (+/- SD) and 38.0 +/- 12.3 y (+/- SD), respectively. The mean BAC for the male DUI suspects was 1.88 +/- 0.748 mg/mL (+/- SD) compared with 1.86 +/- 0.702 (+/- SD) for the females. The relationship between beta-slope (y) and BAC (x) was y = 0.175 + 0.009x with a small positive correlation (r = 0.13) and standard error estimate (Syx) of 0.049 mg/mL. The mean beta-slope for female DUI suspects was 0.214 +/- 0.053 mg/mL/h (+/- SD), compared with 0.189 +/- 0.048 mg/mL/h in the male suspects, and this small difference was statistically highly significant (t = 5.21, p < 0.001). The overall mean rate of alcohol elimination from blood in drinking drivers was 0.191 +/- 0.049 mg/mL/h (+/- SD), and the 95% limits of agreement (LOA) spanned from 0.09 to 0.29 mg/mL/h. The value of the beta-slope was slightly steeper starting from a high initial BAC but was not much influenced by the person's age.