[1] Duke Clin Res Inst, Durham, NC 27705 USA
[2] Duke Univ, Med Ctr, Durham, NC USA
[3] Univ Barcelona, Hosp Clin, IDIBAPS, Barcelona, Spain
[4] Drexel Univ, Coll Med, Philadelphia, PA USA
[5] Sch Publ Hlth, Philadelphia, PA USA
[6] Univ Franche Comte, Ctr Hosp Univ Besancon, Besancon, France
[7] Univ La Mediterranee, Marseille, France
[8] Sahlgrens Univ Hosp, S-41345 Gothenburg, Sweden