title: Opening of ambulatory surgery centers and procedure use in elderly patients: data from Florida.
abstract: BACKGROUND
  Ambulatory surgery centers (ASCs) potentially deliver care more efficiently than hospitals. However, ASC proliferation may increase discretionary surgery use because of financial incentives for the physicians who staff them. To explore this possibility, we measured the impact of the opening of an ASC in a health care market, as defined by the hospital service area (HSA), on rates of procedure use.
  
  
  METHODS
  With a 100% sample of outpatient surgery encounters, we measured annual rates of use for discretionary (cataract surgery, colonoscopy, and upper gastrointestinal [GI] tract endoscopy) and imperative (cancer-directed breast surgery) procedures among Medicare-eligible persons. Using a multiple time series research design, we compared the change in procedure use for HSAs where ASCs opened with that of HSAs where an ASC was never present.
  
  
  METHODS
  Florida HSAs.
  
  
  METHODS
  All patients 65 years or older undergoing outpatient surgery from January 1, 1998, through December 31, 2006. Main Outcome Measure Adjusted HSA-level rates of procedure use.
  
  
  RESULTS
  In HSAs where an ASC opened, colonoscopy use increased by 1610 procedures per 100 000 per year (95% confidence interval, 736-2485; P < .001) and upper GI tract endoscopy use increased by 775 procedures per 100 000 per year (159-1391; P = .01). However, rates of cancer-directed breast surgery remained flat. Among HSAs where an ASC opened, the relative increases in colonoscopy and upper GI tract endoscopy use were approximately 117% and 93% higher, respectively, 4 years after the opening compared with HSAs without ASCs.
  
  
  CONCLUSIONS
  The opening of an ASC within an HSA is associated with significant increases in discretionary surgery use.
authors.affiliation: Dow Division of Health Services Research, Department of Urology, Center for Healthcare Outcomes and Policy, University of Michigan, Ann Arbor, MI 48105-2967, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Hollingsworth
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Krein
authors.forename: Zaojun
authors.initials: Z
authors.lastname: Ye
authors.forename: Hyungjin Myra
authors.initials: HM
authors.lastname: Kim
authors.forename: Brent K
authors.initials: BK
authors.lastname: Hollenbeck
mesh_terms: D000368:Aged; D000556:Ambulatory Surgical Procedures / Q000706:statistics & numerical data*; D003695:Delivery of Health Care / Q000458:organization & administration*; D005431:Florida; D006801:Humans; D012189:Retrospective Studies; D013531:Surgicenters / Q000706:statistics & numerical data*