[1] Univ Calif San Diego, Sch Med, La Jolla, CA 92093 USA
[2] Stanford Univ, Palo Alto, CA 94304 USA
[3] Denver Arthrit Ctr, Denver, CO USA
[4] Univ Calif Irvine, Irvine, CA USA
[5] Univ Arizona, Tucson, AZ USA
[6] Guthrie Clin, Sayre, PA USA
[7] Inst Seguro Social, Tijuana, Mexico
[8] Johns Hopkins Univ, Seattle, WA USA
[9] Mayo Clin, Rochester, MN USA
[10] Altoona Ctr Clin Res, Duncansville, PA USA
[11] Univ Alabama, Sch Publ Hlth, Birmingham, AL 35294 USA
[12] Univ Utrecht, Med Ctr, Utrecht, Netherlands