title: Understanding pre-enrollment surgical outcomes for hospitals participating in Medicare Accountable Care Organizations.
abstract: BACKGROUND
  To anticipate the effects of accountable care organizations (ACOs) on surgical care, we examined pre-enrollment utilization, outcomes, and costs of inpatient surgery among hospitals currently enrolled in Medicare ACOs vs nonenrolling facilities.
  
  
  METHODS
  Using the Nationwide Inpatient Sample (2007 to 2011), we compared patient and hospital characteristics, distributions of surgical specialty care, and the most common inpatient surgeries performed between ACO-enrolling and nonenrolling hospitals before implementation of Medicare ACOs. We used multivariable regression to compare pre-enrollment inpatient mortality, length of stay (LOS), and costs.
  
  
  RESULTS
  Hospitals now participating in Medicare ACO programs were more frequently nonprofit (P < .001) and teaching institutions (P = .01) that performed more specialty procedures (P < .001). We observed no clinically meaningful pre-enrollment differences for inpatient mortality, prolonged length of stay, or costs for procedures performed at ACO-enrolling vs nonenrolling hospitals.
  
  
  CONCLUSIONS
  Medicare ACO hospitals had pre-enrollment outcomes that were similar to nonparticipating facilities. Future studies will determine whether ACO participation yields differential changes in surgical quality or costs.
authors.affiliation: Department of Urology, University of Michigan, NCRC Building 16, Room 108E, 2800 Plymouth Road, Ann Arbor, MI, 48109-2800, USA.
authors.forename: Scott R
authors.initials: SR
authors.lastname: Hawken
authors.affiliation: Department of Urology, University of Michigan, NCRC Building 16, Room 108E, 2800 Plymouth Road, Ann Arbor, MI, 48109-2800, USA.
authors.forename: Lindsey A
authors.initials: LA
authors.lastname: Herrel
authors.affiliation: Department of Urology, University of Michigan, NCRC Building 16, Room 108E, 2800 Plymouth Road, Ann Arbor, MI, 48109-2800, USA.
authors.forename: Chandy
authors.initials: C
authors.lastname: Ellimoottil
authors.affiliation: Department of Urology, University of Michigan, NCRC Building 16, Room 108E, 2800 Plymouth Road, Ann Arbor, MI, 48109-2800, USA.
authors.forename: Zachary A
authors.initials: ZA
authors.lastname: Montgomery
authors.affiliation: Department of Urology, University of Michigan, NCRC Building 16, Room 108E, 2800 Plymouth Road, Ann Arbor, MI, 48109-2800, USA.
authors.forename: Zaojun
authors.initials: Z
authors.lastname: Ye
authors.affiliation: Department of Urology, University of Michigan, NCRC Building 16, Room 108E, 2800 Plymouth Road, Ann Arbor, MI, 48109-2800, USA. Electronic address: dcmiller@med.umich.edu.
authors.forename: David C
authors.initials: DC
authors.lastname: Miller
mesh_terms: D060866:Accountable Care Organizations / Q000191:economics*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D032882:Comprehension; D016208:Databases, Factual; D005260:Female; D017048:Health Care Costs; D018166:Health Care Reform; D006761:Hospitals / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D006278:Medicare / Q000191:economics* / Q000706:statistics & numerical data; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011050:Policy Making; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D013514:Surgical Procedures, Operative / Q000191:economics* / Q000379:methods; D014481:United States
keywords: Accountable care organizations; Costs; Policy; Quality improvement; Surgery