[1] Brigham & Womens Hosp, Div Pharmacoepidemiol & Pharmacoecon, Dept Med, 1620 Tremont St,Ste 3030, Boston, MA 02120 USA
[2] Harvard Med Sch, 1620 Tremont St,Ste 3030, Boston, MA 02120 USA
[3] Univ N Carolina, Dept Epidemiol, Chapel Hill, NC 27515 USA
[4] Univ Penn, Dept Epidemiol & Biostat, Perelman Sch Med, Ctr Clin Epidemiol & Biostat, Philadelphia, PA 19104 USA
[5] Univ Penn, Perelman Sch Med, Div Rheumatol, Philadelphia, PA 19104 USA
[6] Brigham & Womens Hosp, Div Rheumatol Immunol & Allergy, 75 Francis St, Boston, MA 02115 USA