[1] Mayo Clin, Div Rheumatol, Dept Med, Rochester, MN USA
[2] Mayo Clin, Div Biomed Stat & Informat, Dept Hlth Sci Res, Dept Med, Rochester, MN USA
[3] Univ Calif Los Angeles, Div Rheumatol, Los Angeles, CA USA
[4] Clin Alemana Santiago, Dept Internal Med, Rheumatol Unit, Santiago, Chile
[5] Mayo Clin, Div Epidemiol, Dept Hlth Sci Res, Rochester, MN USA