No evidence that designated driver programs stop drunken driving

May 19 2005

Publicity campaigns can produce small, fleeting increases in the number of designated drivers, but there is not enough evidence to show whether these programs decrease drunk driving, according to a new review of studies.

Lead researcher Randy Elder and colleagues found few studies that measured the effectiveness of designated driver programs, despite their popularity in the United States and elsewhere since the 1980s. The report was produced by the U.S. Task Force on Community Preventive Services, an independent advisory panel of experts funded by the federal government and reported in the most recent American Journal of Preventive Medicine.

Designated drivers are people who drink no alcohol at a bar, restaurant or other drinking establishment and agree to drive other members of their party home. In practice, according to Elder, only a few designated drivers completely abstain from alcohol.

“In some cases, the designated driver may be chosen based on who among the group is the least intoxicated,” Elder says.

“When an intended designated driver becomes intoxicated, this leaves group members with a difficult choice between having the least drunk person drive them home or arranging for alternative transportation,” he explains.

In one Australian study of a designated-driver media campaign, there was a 13 percentage point change in the number of people interviewed who said they would always use a designated driver. However, there was no change in the percentage of people who said they drove drunk or rode with someone who had been drinking after the media campaign.

In eight other studies of programs at bars that offered free food and other incentives to designated drivers, the giveaways produced only one more designated driver a night, on average.

In two of the studies, the increase in designated drivers disappeared immediately after the free offers were discontinued, say Elder and colleagues.

The incentive programs worked best in bars and other establishments that promoted the program heavily, the researchers found.

“For example, in one study, 42 percent of patrons of the nightclub with the most enthusiastic promotion by door staff reported participating in the designated driver program, while the least enthusiastic nightclub had only 12 percent participation,” Elder and colleagues write.

Elder says no studies have examined whether the use of designated drivers actually decreases alcohol-related car crashes and injuries.

“Until we have stronger evidence regarding the effects of incentive programs on these variables, it will be difficult to determine their public health impact,” he says.

The researchers say there is not enough evidence to know whether peer support groups, like Students Against Destructive Decisions, and campus campaigns to convince students that most of their peers are light drinkers have any effect on drinking and driving.

If a crash occurs, anyone in the car who has been drinking may suffer more severe injuries, says Dr. Ronald Maio, an emergency room physician and professor of emergency medicine at the University of Michigan.

“For some reason, alcohol seems to decrease the body’s tolerance to the forces one experiences in a crash,” says Maio. “Even with every safety precaution, the fact is that if you have alcohol in your system and you’re involved in a motor vehicle crash, your injuries are going to be worse than if you didn’t have alcohol in your system at the time.”

In another finding, the Task Force found that school programs to convince children not to ride with drivers who have been drinking do work but apparently do not reduce the incidence of teens drinking and driving.