[1] Univ N Carolina, Dept Emergency Med, Carolina Ctr Hlth Informat, Chapel Hill, NC USA
[2] Univ N Carolina, Injury Prevent Res Ctr, Chapel Hill, NC USA
[3] Univ N Carolina, Highway Safety Res Ctr, Chapel Hill, NC USA
[4] North Carolina Injury & Violence Prevent Branch, Div Publ Hlth, Raleigh, NC USA
[5] Univ N Carolina, Dept Epidemiol, Chapel Hill, NC USA