[1] Univ Med & Dent New Jersey, Robert Wood Johnson Med Sch, Div Res, Dept Family Med, Somerset, NJ 08873 USA
[2] Virginia Commonwealth Univ, Dept Family Med, Richmond, VA USA
[3] Virginia Commonwealth Univ, Dept Epidemiol & Community Hlth, Richmond, VA USA
[4] Michigan State Univ, Dept Family Med, E Lansing, MI 48824 USA
[5] Univ N Carolina, Dept Family Med, Chapel Hill, NC 27514 USA
[6] Case Western Reserve Univ, Dept Family Med Epidemiol & Biostat, Cleveland, OH 44106 USA
[7] Case Comprehens Canc Ctr, Cleveland, OH USA
[8] Univ Texas Hlth Sci Ctr San Antonio, San Antonio, TX 78229 USA
[9] Dartmouth Coll, Hitchcock Med Ctr, Dartmouth Med Sch, Dept Pediat,Dept Community & Family Med, Lebanon, NH 03756 USA