[1] Univ Virginia, Hlth Syst, Dept Hlth Evaluat Sci, Sch Med, Charlottesville, VA 22908 USA
[2] Univ Virginia, Sch Med, Dept Obstet & Gynecol, Charlottesville, VA 22908 USA
[3] Univ Virginia, Sch Med, Charlottesville, VA 22903 USA
[4] FMAS Corp, DynCorp HITS, Rockville, MD USA