[1] Univ Wisconsin, Dept Surg, Wisconsin Surg Outcomes Res Grp, Div Otolaryngol, Madison, WI 53706 USA
[2] Massachusetts Eye & Ear Infirm, Div Thyroid & Parathyroid Endocrine Surg, Boston, MA USA
[3] Harvard Med Sch, Dept Otolaryngol, Boston, MA USA
[4] Dept Vet Affairs Med Ctr, VA Outcomes Grp, White River Jct, VT USA
[5] Geisel Sch Med Dartmouth, Sect Otolaryngol, White River Jct, VT USA
[6] Dartmouth Inst Hlth Policy & Clin Practice, Lebanon, NH USA