A substantial number of drivers with high blood alcohol concentrations who are killed in automobile crashes are not problem drinkers, according to a study conducted by the Johns Hopkins Bloomberg School of Public Health and the Insurance Institute for Highway Safety. The study examined the relationship between the drivers' drinking habits, as reported by family members, and blood alcohol concentrations at the time of death.
The findings, which appear in the September issue of Injury Prevention, suggest that prevention efforts addressing alcohol-impaired driving should target a wide spectrum of drinking drivers in addition to the so-called hard-core offenders. The latter are defined as people with drinking problems who frequently drive while impaired by alcohol and resist changing their behavior.
The researchers defined potential problem drinkers using several different measures. A problem drinker is often defined as someone who experiences emotional or physical problems because of drinking, or who has family, work, legal or financial problems caused by drinking.
"Our study found a strong association between blood alcohol concentrations at the time of death and a history of problem drinking. However, more than 40 percent of the drivers we studied with very high blood alcohol levels were not reported to have either of the two strongest indicators of problem drinking by their spouses, who appeared to be the most credible respondents," said Susan Baker, lead author of the study and a professor of health policy and management at the Bloomberg School.
For the study, Baker and her colleagues analyzed the blood alcohol concentrations and drinking habits of 818 drivers killed in automobile crashes, using data from the Fatality Analysis Reporting System and the National Mortality Followback Survey, which surveyed spouses and close relatives about the deceased drivers' drinking habits.
The study found that a substantial proportion of the deceased drivers were not identified as problem drinkers, although there was a strong association between blood alcohol concentrations, or BACs, and drinking history. Depending on the problem-drinking indicator, 21 percent to 61 percent of deceased drivers with very high BACs (0.15 g/dL or higher) met the criteria for problem drinking. About 21 percent of drivers with very high BACs were reported as driving within two hours of consuming five or more drinks at least once a month, compared with 2 percent of those with zero BACs. Relatives described 31 percent of deceased drivers with very high BACs as problem drinkers, compared with only 1 percent of drivers with a BAC of zero. Sixty-one percent of drivers with very high BACs were classified as heavy drinkers, compared with 7 percent with zero BACs.
The legal standard for intoxication in 33 states is a BAC of 0.08 g/dL or higher (two other states will have 0.08 standards starting in 2003). In other states, it is 0.10 g/dL or higher. The study also found that only 7 percent of the deceased drivers had been convicted of alcohol-impaired driving in the three years prior to their fatal crash; 19 percent of the drivers with very high BACs had such a conviction in their driving records.
The study was funded by the Insurance Institute for Highway Safety and the Centers for Disease Control and Prevention.