[1] Columbia Univ, Med Ctr, Dept Med, New York, NY 10032 USA
[2] Columbia Univ, Med Ctr, Dept Epidemiol, New York, NY 10032 USA
[3] Hankinson Consulting Inc, Valdosta, GA USA
[4] Univ Penn, Sch Med, Dept Med, Philadelphia, PA 19104 USA
[5] Univ Penn, Sch Med, Ctr Clin Epidemiol & Biostat, Philadelphia, PA 19104 USA
[6] Univ Arizona, Div Epidemiol & Biostat, Tucson, AZ USA
[7] Northwestern Univ, Dept Med, Chicago, IL 60611 USA
[8] Univ Washington, Dept Biostat, Seattle, WA 98195 USA