Ignition lock laws cut alcohol-related crash deaths

Reuters Health - States that require convicted drunk drivers to install ignition interlock devices in their cars had a 15 percent drop in alcohol-related crash deaths compared to states without these requirements, research shows.

Ignition interlocks use a built-in breath analyzer. If the driver’s blood alcohol limit is above the programmed limit - usually 0.02 grams per deciliter - the car does not start.

“We were able to see a real improvement in states that require them for all drunk driving convictions,” said lead author Elinore J. Kaufman, a student with the Health Policy Program at the University of Pennsylvania in Philadelphia.

A 15 percent decrease in deaths represents “a big change,” Kaufman told Reuters Health by phone.

While every state in the U.S. has some ignition interlock legislation, not all require them. Between 2004 and 2013, 18 states made ignition interlocks mandatory for all drunk driving convictions. (Today the number of states with those laws has grown to 23, according to the National Conference of State Legislatures.)

The researchers used data from the National Highway Traffic Safety Administration for 1999 to 2013, including alcohol involved crash deaths in those 18 states and in the 32 states without interlock requirements.

In the country as a whole, alcohol-related crash death rates rose from 6.1 to 6.4 per 100,000 people per year between 1999 and 2001, then fell to 4.3 deaths by 2013.

There were very small decreases in alcohol-related crash deaths in states with universal interlock laws in the two years after implementation, which dipped considerably in year three compared to states without the laws.

Accounting for year, vehicle miles traveled per state and other factors, states with universal interlock laws had 4.7 alcohol related crash deaths per 100,000 people per year, a 15 percent reduction from the 5.5 deaths in states without the laws, as reported in the American Journal of Public Health.

Crash-related deaths that did not involve alcohol were not different between interlock and non-interlock states.

“Between 2004 and 2013 more than 900 lives were saved, and if every state had this law it would be 2,600 lives,” Kaufman said.

“Taking the decision out of the hands of people when they’re already drunk and making it easier on police can really make a big difference,” she said.

The interlock devices cost around $150 to buy and install, and the individual required to have it is responsible for the expense, Kaufman said.

“It appears that a large number of deaths can be prevented with this intervention,” said Dr. Timothy Naimi of the Boston University School of Medicine Clinical Addiction Research and Education Unit, who was not part of the new study.

But “it’s very important to understand for the public that it probably takes a minimum of 100 episodes of impaired driving before one is caught, and oftentimes they are not convicted,” Naimi told Reuters Health by phone. “Interlocks are an important piece of the puzzle, but not a cure-all.”

“Although it’s still possible for drivers under interlock orders to drink and drive (by using a different car), interlocks have been shown to reduce the likelihood of a drink-driving re-arrest by more than half,” said Charles M. Farmer, vice president of Research and Statistical Services for the Insurance Institute for Highway Safety in Ruckersville, Virginia. “This is an important step in stopping drivers who habitually drink and drive, but these drivers are only part of the problem.”

“Most alcohol-impaired drivers do not have any DUI convictions on their record, so they will not have been assigned an interlock,” Farmer told Reuters Health by email.

SOURCE: American Journal of Public Health, online March 17, 2016.