Tighter Laws May Eliminate Racial Differences in Seat Belt Use

NASHVILLE, Tenn., June 20 - If the U.S. states with loose seat belt laws tightened them, the disparity in seat belt use between blacks and whites might disappear, researchers here said.

In states with so-called secondary seat belt laws, in which unbuckled drivers can be cited only if they are stopped for another offense, blacks are 11% less likely than whites to wear seat belts, said Nathaniel C. Briggs, M.D., of the Meharry Medical College here.

But in states with primary laws, where drivers can be stopped solely for not wearing a seat belt, seat belt use among blacks and whites is virtually identical, Dr. Briggs and colleagues said in the August issue of the American Journal of Preventive Medicine.

Twenty-five states have primary laws, 24 have secondary laws, and one state, New Hampshire, has no seat belt laws, the authors said.

Previous research has established that rates of seat belt use tend to be lower among blacks than whites and that a disproportionately high proportion of crash fatalities involve blacks, the researchers said.

The current study examined data on more than 11,000 blacks and more than 73,000 whites 16 or older who were fatally injured in car crashes from 1999 to 2003. The data were from the Fatality Analysis Reporting Systems, which is maintained by the National Highway Traffic Safety Administration.

In states with secondary seat belt laws, 36% of whites and 28% of blacks had been wearing seat belts at the time of the accident. After adjusting for factors such as age, gender, and seat position, the odds ratio for seat belt use among blacks compared with whites was 0.89 (95% confidence interval=0.83 to 0.95).

In these states, the lower prevalence of seat belt use among blacks was most pronounced in urban areas, where blacks were 25% less likely than whites to buckle up (OR=0.75; 95% CI=0.67 to 0.84).

In states with primary laws, 51% of whites and 46% of blacks had been wearing their seat belts. In these states, the odds of buckling up were not significantly different between blacks and whites. (OR=1.05; 95% CI=0.97 to 1.13).

The disparities in seat belt use were most dramatic in the youngest age group, 16 to 29 year olds, and in the oldest age group, those 50 or older, the researchers noted.

"Because motorists buckle up less often on short trips than when traveling long distances, one explanation for the greater magnitude of black-white disparities at extremes of driving age may be that blacks travel less or take more short trips than whites," the authors said.

"Likewise, the finding that seat belt use among blacks was significantly lower than among whites only in urban areas of secondary-law states could reflect a greater concentration of blacks in the inner city, where speed limits tend to be lower and points of destination are often closer than comparable points in more outlying areas," they added.

Other researchers have suggested that blacks may be more likely to buckle up in states with primary seat belt laws because of concern they will be disproportionately targeted by police for not wearing their seat belts, the authors said.

A chief limitation of the study was that it included only those who died in car crashes and, therefore, residual confounding from factors other than seat belt use may have affects the results, the authors said.

Nevertheless, the study "suggests that black-white disparities in seat belt use could be reduced or eliminated if states with secondary seat belt laws upgraded to primary enforcement," the authors concluded.

Previous research suggests that buckling up reduces the risk of mortality in a car crash by 50% or more, they added.