[1] Durham Vet Affairs Med Ctr, Hlth Serv Res & Dev Serv, Durham, NC USA
[2] Duke Univ, Dept Med, Med Ctr, Div Gen Internal Med, Durham, NC 27706 USA
[3] Univ N Carolina, Thurston Arthrit Res Ctr, Chapel Hill, NC USA
[4] Univ N Carolina, Dept Med, Chapel Hill, NC USA
[5] Univ N Carolina, Dept Orthopaed, Chapel Hill, NC USA
[6] Univ N Carolina, Dept Social Med, Chapel Hill, NC USA
[7] Univ N Carolina, Dept Epidemiol, Chapel Hill, NC USA
[8] Univ N Carolina, Dept Radiol, Chapel Hill, NC USA
[9] Univ So Calif, Keck Sch Med, Dept Prevent Med, Los Angeles, CA 90033 USA
[10] Ctr Dis Control & Prevent, Atlanta, GA USA