[1] Univ Calif Los Angeles, Sch Med, Los Angeles, CA USA
[2] Philadelphia VA Med Ctr, Ctr Hlth Equity Res & Promot, Philadelphia, PA USA
[3] Litchfield Family Practice Ctr, Litchfield, IL USA
[4] Univ Utah, Pain Management Ctr, Salt Lake City, UT USA
[5] Victory Springs Senior Hlth Associates, Baltimore, MD USA
[6] Johns Hopkins Univ, Sch Med, Baltimore, MD USA
[7] Univ Iowa, Iowa City, IA USA
[8] Univ Rochester, Sch Med, Rochester, NY USA
[9] Duke Med Ctr, Durham, NC USA
[10] Univ Calif San Francisco, San Francisco, CA 94143 USA
[11] Emory Univ, Sch Med, Atlanta, GA USA
[12] St Louis Univ, St Louis, MO 63103 USA
[13] Wayne State Univ, Detroit, MI USA
[14] Univ Pittsburgh, Sch Med, Pain Evaluat & Treatment Inst, Pittsburgh, PA USA