title: Surgical safety and hospital volume across a wide range of interventions.
abstract: OBJECTIVE
  For certain major operations, inpatient mortality risk is lower in high-volume hospitals than those in low-volume hospitals. Extending the analysis to a broader range of interventions and outcomes is necessary before adopting policies based on minimum volume thresholds.
  
  
  METHODS
  Using the United States 2004 Nationwide Inpatient Sample, we assessed the effect of intervention-specific and overall hospital volume on surgical complications, potentially avoidable reoperations, and deaths across 1.4 million interventions in 353 hospitals. Outcome variations across hospitals were analyzed through a 3-level hierarchical logistic regression model (patients, surgical interventions, and hospitals), which took into account interventions on multiple organs, 144 intervention categories, and structural hospital characteristics. Discriminative performance and calibration were good.
  
  
  RESULTS
  Hospitals with more experience in a given intervention had similar reoperation rates but lower mortality and complication rates: odds ratio per volume deciles 0.93 and 0.97. However, the benefit was limited to heart surgery and a small number of other operations. Risks were higher for hospitals that performed more interventions overall: odds ratio per 1000 for each event was approximately 1.02. Even after adjustment for specific volume, mortality varied substantially across both high- and low-volume hospitals.
  
  
  CONCLUSIONS
  Although the link between specific volume and certain inpatient outcomes suggests that specialization might help improve surgical safety, the variable magnitude of this link and the heterogeneity of hospital effect do not support the systematic use of volume-based referrals. It may be more efficient to monitor risk-adjusted postoperative outcomes and to investigate facilities with worse than expected outcomes.
authors.affiliation: Institute of Health Economics and Management, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Lausanne, Switzerland. yves.eggli@bluewin.ch
authors.forename: Yves
authors.initials: Y
authors.lastname: Eggli
authors.forename: Patricia
authors.initials: P
authors.lastname: Halfon
authors.forename: Danielle
authors.initials: D
authors.lastname: Meylan
authors.forename: Patrick
authors.initials: P
authors.lastname: Taffé
mesh_terms: D002423:Cause of Death; D017052:Hospital Mortality / Q000639:trends*; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D008505:Medical Staff, Hospital / Q000706:statistics & numerical data; D009873:Operating Rooms / Q000706:statistics & numerical data; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D011183:Postoperative Complications / Q000401:mortality*; D012042:Registries / Q000706:statistics & numerical data; D017751:Safety Management / Q000706:statistics & numerical data*; D013514:Surgical Procedures, Operative / Q000009:adverse effects / Q000706:statistics & numerical data*; D014481:United States / Q000453:epidemiology; D014940:Work Schedule Tolerance; D016526:Workload / Q000706:statistics & numerical data*