[1] Mayo Clin, Dept Hlth Sci Res, 200 1st St SW, Rochester, MN 55905 USA
[2] Penn State Univ, Hershey Med Sch, Dept Biobehav Hlth, State Coll, PA USA
[3] Penn State Univ, Hershey Med Sch, Dept Hlth Evaluat Sci, State Coll, PA USA
[4] Univ N Carolina, Sch Publ Hlth, Dept Epidemiol, Chapel Hill, NC USA
[5] Merck Res Labs, West Point, PA USA
[6] United BioSource Corp, Ctr Hlth Outcomes Res, Bethesda, MD USA