[1] Univ Luzern, Div Hematol, Luzerner Kantonsspital, Luzern, Switzerland
[2] Univ Oklahoma, Hlth Sci Ctr, Hudson Coll Publ Hlth, Dept Biostat & Epidemiol, Oklahoma City, OK USA
[3] Univ Oklahoma, Hlth Sci Ctr, 801 NE 13th St,Coll Hlth Bldg,Room 333, Oklahoma City, OK 73104 USA