title: An evaluation of surgical site infections by wound classification system using the ACS-NSQIP.
abstract: BACKGROUND
  Surgical wound classification has been the foundation for infectious risk assessment, perioperative protocol development, and surgical decision-making. The wound classification system categorizes all surgeries into: clean, clean/contaminated, contaminated, and dirty, with estimated postoperative rates of surgical site infection (SSI) being 1%-5%, 3%-11%, 10%-17%, and over 27%, respectively. The present study evaluates the associated rates of the SSI by wound classification using a large risk adjusted surgical patient database.
  
  
  METHODS
  A cross-sectional study was performed using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) dataset between 2005 and 2008. All surgical cases that specified a wound class were included in our analysis. Patient demographics, hospital length of stay, preoperative risk factors, co-morbidities, and complication rates were compared across the different wound class categories. Surgical site infection rates for superficial, deep incisional, and organ/space infections were analyzed among the four wound classifications using multivariate logistic regression.
  
  
  RESULTS
  A total of 634,426 cases were analyzed. From this sample, 49.7% were classified as clean, 35.0% clean/contaminated, 8.56% contaminated, and 6.7% dirty. When stratifying by wound classification, the clean, clean/contaminated, contaminated, and dirty wound classifications had superficial SSI rates of 1.76%, 3.94%, 4.75%, and 5.16%, respectively. The rates of deep incisional infections were 0.54%, 0.86%, 1.31%, and 2.1%. The rates for organ/space infection were 0.28%, 1.87%, 2.55%, and 4.54%.
  
  
  CONCLUSIONS
  Using ACS-NSQIP data, the present study demonstrates substantially lower rates of surgical site infections in the contaminated and dirty wound classifications than previously reported in the literature.
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21287-0005, USA.
authors.forename: Gezzer
authors.initials: G
authors.lastname: Ortega
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Rhee
authors.forename: Dominic J
authors.initials: DJ
authors.lastname: Papandria
authors.forename: Jessica
authors.initials: J
authors.lastname: Yang
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Ibrahim
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Shore
authors.forename: Martin A
authors.initials: MA
authors.lastname: Makary
authors.forename: Fizan
authors.initials: F
authors.lastname: Abdullah
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007902:Length of Stay; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D013530:Surgical Wound Infection / Q000453:epidemiology*; D014947:Wounds and Injuries / Q000145:classification