[1] Univ Florida, Hlth Sci Ctr Lib, POB 100206, Gainesville, FL 32610 USA
[2] West Virginia Univ, Sch Publ Hlth, Dept Biostat, HSC N, POB 9190, Morgantown, WV 26506 USA
[3] Kaiser Permanente, Washington Hlth Res Inst, Seattle, WA USA
[4] Ohio State Univ, Coll Med, Dept Family Med, Columbus, OH 43210 USA
[5] West Virginia Univ, Sch Publ Hlth, HSC N, Dept Epidemiol, POB 9190, Morgantown, WV 26506 USA