title: Is the Risk of Wound Infection Related to Bilateral Internal Thoracic Artery Graft Potentiated by Age?
abstract: BACKGROUND
  Older age and the use of bilateral internal thoracic artery (ITA) grafting are both considered risk factors for surgical wound infection (SWI) after coronary artery bypass grafting (CABG). The 2014 European Guidelines recommend that bilateral ITA grafting should be considered in patients aged younger than 70 years. Our aim was to investigate interaction between age and the number of ITA grafts.
  
  
  METHODS
  All patients aged 18 years and older who had undergone CABG with at least 1 ITA at Rouen University Hospital between 2001 and 2012 were selected. Data regarding surgical procedure (single/bilateral ITA grafting) were extracted from the medical information system. SWI was identified from prospective surveillance of patients according to Centers for Disease Control and Prevention criteria. Independent factors associated with SWI were assessed by logistic regression, and an interaction test between age (≤69 or ≥70 years) and the number of ITA grafts was performed.
  
  
  RESULTS
  SWI occurred in 71 of 2,726 patients (2.6%). Bilateral ITA grafting was associated with SWI (adjusted odds ratio [aOR], 2.55; 95% confidence interval, 1.51 to 4.30). After fitting an interaction term between age and number of ITA grafts, the aORs for SWI after bilateral ITA grafting substantially differed between patients aged 69 years and younger (aOR, 1.88; 95% confidence interval, 0.94 to 3.75) and 70 years and older (aOR, 3.52; 95% confidence interval, 1.69 to 7.33). However, this interaction failed to reach statistical significance (p = 0.2213), possibly because of insufficient statistical power (23.5%) despite the large sample size.
  
  
  CONCLUSIONS
  Age 70 years and older compared with age 69 years and younger was associated with higher occurrence of SWI after bilateral ITA grafting, but this interaction was not statistically significant. Larger studies are needed to test this interaction.
authors.affiliation: Department of Epidemiology and Public Health, Rouen University Hospital, Rouen, France. Electronic address: quentin.luzurier@gmail.com.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Luzurier
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Rouen University Hospital, Rouen, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Le Guillou
authors.affiliation: Department of Epidemiology and Public Health, Rouen University Hospital, Rouen, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Lottin
authors.affiliation: Department of Biostatistics, Rouen University Hospital, Rouen, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Vermeulin
authors.affiliation: Department of Epidemiology and Public Health, Rouen University Hospital, Rouen, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Marini
authors.affiliation: Department of Epidemiology and Public Health, Rouen University Hospital, Rouen, France.
authors.forename: Tristan
authors.initials: T
authors.lastname: Petel
authors.affiliation: Department of Epidemiology and Public Health, Rouen University Hospital, Rouen, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Czernichow
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Rouen University Hospital, Rouen, France.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Bessou
authors.affiliation: Department of Biostatistics, Rouen University Hospital, Rouen, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Bénichou
authors.affiliation: Department of Epidemiology and Public Health, Rouen University Hospital, Rouen, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Merle
mesh_terms: D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D015331:Cohort Studies; D017023:Coronary Angiography / Q000379:methods; D001026:Coronary Artery Bypass / Q000009:adverse effects* / Q000379:methods*; D023921:Coronary Stenosis / Q000000981:diagnostic imaging / Q000401:mortality / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D005602:France; D006785:Hospitals, University; D006801:Humans; D016015:Logistic Models; D008297:Male; D008323:Mammary Arteries / Q000637:transplantation*; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D013530:Surgical Wound Infection / Q000175:diagnosis* / Q000453:epidemiology; D016896:Treatment Outcome