Crash Risk of Alcohol Impaired Driving

In order to determine the relative crash risk of drivers at various blood alcohol concentration (BAC) levels a case-control study was conducted in Long Beach, CA and Fort Lauderdale, FL. Data was collected on 4,919 drivers involved in 2,871 crashes of all severities. In addition, two drivers at the same location, day of week and time of day were sampled a week after a crash, which produced 10,066 control drivers. Thus, a total of 14,985 drivers were included in the study. Relative risk models were generated using logistic regression techniques with and without covariates such as driver age, gender, marital status, drinking frequency and ethnicity. The overall result was in agreement with previous studies in showing increasing relative risk as BAC increases, with an accelerated rise at BACs in excess of.10 BAC. After adjustments for missing data (hit-and-run drivers, refusals, etc.) the result was an even more dramatic rise in risk, with increasing BAC that began at lower BACs (above.03 BAC)