[1] Johns Hopkins Med Inst, Dept Otolaryngol Head & Neck Surg, Baltimore, MD USA
[2] Johns Hopkins Sch Med, Dept Otolaryngol Head & Neck Surg, Baltimore, MD USA
[3] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Hlth Policy & Management, Baltimore, MD USA
[4] Johns Hopkins Med Inst, Armstrong Inst Patient Safety & Qual, Baltimore, MD USA