title: Effect of wound classification on risk adjustment in American College of Surgeons NSQIP.
abstract: BACKGROUND
  Surgical wound classification has been used in risk-adjustment models. However, it can be subjective and could potentially improperly bias hospital quality comparisons. The objective is to examine the effect of wound classification on hospital performance risk-adjustment models.
  
  
  METHODS
  Retrospective review of the 2011 American College of Surgeons NSQIP database was conducted for the following wound classification categories: clean, clean-contaminated, contaminated, and dirty-infected. To assess the influence of wound classification on risk adjustment, 2 models were developed for all outcomes: 1 including and 1 excluding wound classification. For each model, hospital postoperative complications were estimated using hierarchical multivariable regression methods. Absolute changes in hospital rank, correlations of odds ratios, and outlier status agreement between models were examined.
  
  
  RESULTS
  Of the 442,149 cases performed in 315 hospitals: 53.6% were classified as clean; 34.2% as clean-contaminated; 6.7% as contaminated; and 5.5% as dirty-infected. The surgical site infection rate was highest in dirty-infected (8.5%) and lowest in clean (1.8%) cases. For overall surgical site infection, the absolute change in risk-adjusted hospital performance rank between models, including vs excluding wound classification, was minimal (mean 4.5 of 315 positions). The correlations between odds ratios of the 2 performance models were nearly perfect (R = 0.9976, p < 0.0001), and outlier status agreement was excellent (κ = 0.95ss08, p < 0.0001). Similar findings were observed in models of subgroups of surgical site infections and other postoperative outcomes.
  
  
  CONCLUSIONS
  In circumstances where alternate information is available for risk adjustment, there appear to be minimal differences in performance models that include vs exclude wound classification. Therefore, the American College of Surgeons NSQIP is critically evaluating the continued use of wound classification in hospital performance risk-adjustment models.
authors: Division of Research and Optimal Patient Care, American College of Surgeons, Chicago, IL; Surgical Outcomes and Quality Improvement Center, Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL; Northwestern Memorial Hospital, Chicago, IL. Electronic address: mju@facs.org.
authors: Mila H
authors: MH
authors: Ju
authors: Division of Research and Optimal Patient Care, American College of Surgeons, Chicago, IL.
authors: Mark E
authors: ME
authors: Cohen
authors: Division of Research and Optimal Patient Care, American College of Surgeons, Chicago, IL; Surgical Outcomes and Quality Improvement Center, Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL; Northwestern Memorial Hospital, Chicago, IL.
authors: Karl Y
authors: KY
authors: Bilimoria
authors: Division of Research and Optimal Patient Care, American College of Surgeons, Chicago, IL.
authors: Melissa S
authors: MS
authors: Latus
authors: Division of Research and Optimal Patient Care, American College of Surgeons, Chicago, IL.
authors: Lisa M
authors: LM
authors: Scholl
authors: Division of Research and Optimal Patient Care, American College of Surgeons, Chicago, IL.
authors: Bradley J
authors: BJ
authors: Schwab
authors: Division of Research and Optimal Patient Care, American College of Surgeons, Chicago, IL.
authors: Claudia M
authors: CM
authors: Byrd
authors: Division of Research and Optimal Patient Care, American College of Surgeons, Chicago, IL; Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA.
authors: Clifford Y
authors: CY
authors: Ko
authors: Surgery Department, University of Washington School of Medicine, Seattle, WA.
authors: E Patchen
authors: EP
authors: Dellinger
authors: Division of Research and Optimal Patient Care, American College of Surgeons, Chicago, IL; Department of Surgery, Washington University in St Louis, St Louis, MO; Olin Business School and Center for Health Policy, Washington University in St Louis, St Louis, MO; St Louis VA Medical Center, BJC Healthcare, St Louis, MO.
authors: Bruce L
authors: BL
authors: Hall
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058996:Quality Improvement; D012189:Retrospective Studies; D020379:Risk Adjustment; D012955:Societies, Medical; D013043:Specialties, Surgical; D013530:Surgical Wound Infection / Q000145:classification*; D014481:United States