[1] Merck & Co Inc, Whitehouse Stn, NJ USA
[2] Rutgers State Univ, Piscataway, NJ 08855 USA
[3] C Argerich Hosp, Dept Rheumatol, Buenos Aires, DF, Argentina
[4] Hosp Aranda Parra, Fac Med Leon, Leon, GTO, Mexico
[5] Univ Carabobo, Dept Med, Valencia, Venezuela
[6] Hosp Cent Fuerza Aerea, Lima, Peru
[7] UNICAMP, Campinas, SP, Brazil
[8] UNIFESP, EPM, Dept Med, Disciplina Reumatl, San Jose, Costa Rica
[9] Univ Liege, WHO Collaborat Ctr Publ Hlth Aspects Rheumat Diso, B-4000 Liege, Belgium