title: Preoperative risk prediction of surgical site infection requiring hospitalization or reoperation in patients undergoing vascular surgery.
abstract: The objective of this study was to develop a surgical site infection (SSI) prediction score for risk assessment before elective vascular surgery.
  
  
  
  We conducted a nested case-control study among patients who underwent elective vascular (abdominal aortic and peripheral arterial) surgery from January 1, 2003, to December 31, 2007, at Mayo Clinic (Rochester, Minn) an academic tertiary surgical center. Cases were patients with SSI requiring hospitalization; controls (one or two per case) were matched on type of procedure and date of surgery. Clinical data were collected by chart review. A risk score based on preoperative variables was developed using multivariable logistic regression and bootstrap resampling. The C statistic, equivalent to the area under the receiver operating characteristic curve, was used to assess discrimination. Calibration was assessed by plotting percentile risk groups of model-predicted values against observed proportions of subjects with SSI.
  
  
  
  Eighty-four cases were compared with 160 controls. Preoperative variables independently associated with SSI risk were critical limb ischemia, previous SSI, prior revascularization procedure, and chronic obstructive pulmonary disease. A prediction model containing these variables was developed (model and risk score C statistic of 0.737 and 0.727, respectively). The calibration curve did not appear to deviate appreciably from the 45-degree line of identity.
  
  
  
  We developed an SSI risk score based on noninvasive preoperative variables with acceptable discrimination and calibration. This tool needs prospective and external validation.
authors.affiliation: Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Md. Electronic address: sleekha@epi.umaryland.edu.
authors.forename: Surbhi
authors.initials: S
authors.lastname: Leekha
authors.affiliation: Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minn.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Lahr
authors.affiliation: Division of Infectious Diseases, Mayo Clinic, Rochester, Minn.
authors.forename: Rodney L
authors.initials: RL
authors.lastname: Thompson
authors.affiliation: Division of Infectious Diseases, Mayo Clinic, Rochester, Minn.
authors.forename: Priya
authors.initials: P
authors.lastname: Sampathkumar
authors.affiliation: Division of Vascular and Endovascular Surgery, Mayo Clinic, Rochester, Minn.
authors.forename: Audra A
authors.initials: AA
authors.lastname: Duncan
authors.affiliation: Division of Infectious Diseases, Mayo Clinic, Scottsdale, Ariz.
authors.forename: Robert
authors.initials: R
authors.lastname: Orenstein
mesh_terms: D000368:Aged; D001012:Aorta, Abdominal / Q000601:surgery*; D001018:Aortic Diseases / Q000150:complications / Q000175:diagnosis / Q000601:surgery*; D016022:Case-Control Studies; D016638:Critical Illness; D003661:Decision Support Techniques; D017558:Elective Surgical Procedures; D005260:Female; D006801:Humans; D007511:Ischemia / Q000150:complications / Q000175:diagnosis / Q000601:surgery*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008910:Minnesota; D015999:Multivariate Analysis; D010359:Patient Readmission; D058729:Peripheral Arterial Disease / Q000150:complications / Q000175:diagnosis / Q000601:surgery*; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000379:methods*; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications; D012086:Reoperation; D018570:Risk Assessment; D012307:Risk Factors; D013530:Surgical Wound Infection / Q000175:diagnosis / Q000382:microbiology / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome; D014656:Vascular Surgical Procedures / Q000009:adverse effects*