[1] Johns Hopkins Univ, Sch Med, Dept Surg, Ctr Surg Outcomes Res, Baltimore, MD 21231 USA
[2] Johns Hopkins Univ, Qual & Safety Res Grp, Dept Anesthesiol, Baltimore, MD 21231 USA
[3] Johns Hopkins Univ, Dept Surg, Johns Hopkins Bayview Med Ctr, Baltimore, MD 21231 USA
[4] Johns Hopkins Univ, Sch Med, Dept Hlth Policy & Management, Baltimore, MD 21231 USA
[5] Johns Hopkins Univ, Bloomberg Sch Publ Hlth, Sch Nursing, Baltimore, MD 21231 USA
[6] Yale Univ, Sch Med, New Haven, CT USA
[7] Yale Univ, Sch Management, New Haven, CT USA