[1] Ctr Dis Control & Prevent, Cardiovasc Hlth Branch, Natl Ctr Chron Dis Prevent & Hlth Promot, Atlanta, GA 30341 USA
[2] Johns Hopkins Univ, Bloomberg Sch Publ Hlth, Dept Epidemiol, Baltimore, MD USA
[3] N Carolina Dept Hlth & Human Serv, Injury & Violence Prevent Unit, Raleigh, NC USA
[4] Univ N Carolina, Sch Publ Hlth, Dept Epidemiol, Chapel Hill, NC USA