title: How Long Is Long Enough to Identify a Surgical Site Infection?
abstract: BACKGROUND
  The U.S. Centers for Disease Control requires 90 days after surgery using an implant to diagnose or show the absence of a surgical site infection (SSI). However, many databases only track outcomes up to 30 days. The cost and effort to increase follow-up to 90 days after surgery is high and the benefit is unclear. We hypothesize that the majority of SSIs after ventral hernia repair occur within 30 days of surgery.
  
  
  METHODS
  All patients who underwent ventral hernia repair (with or without mesh) from 2010-2015 at a single institution were evaluated for evidence of SSI. The duration between surgery and the diagnosis of a post-operative SSI was assessed. Baseline and operative characteristics were compared between patients with an early SSI (within 30 days of surgery) and those with a late SSI (more than 30 days after surgery).
  
  
  RESULTS
  Among 1,635 patients who underwent ventral hernia repair, 117 (7.2%) developed an SSI. The median (range) of days between surgery and SSI was 15 days (range, 2-763). There were 20 (17.1%) late SSIs diagnosed; of these, 17 were diagnosed between 31-90 d and three were diagnosed later than 90 days. Patients with a late SSI were more likely to have had a prior ventral hernia repair and have had biologic mesh (p = 0.001).
  
  
  CONCLUSIONS
  Whereas the majority of SSIs after ventral hernia repair occurred within the first 30 days, a substantial number of late SSIs occurred. It is worthwhile to follow patients for at least 90 days post-operative in order to capture a more accurate picture of the true rate of SSI.
authors.affiliation: Department of Surgery, University of Texas Health Science Center at Houston , Houston, Texas.
authors.forename: Julie L
authors.initials: JL
authors.lastname: Holihan
authors.affiliation: Department of Surgery, University of Texas Health Science Center at Houston , Houston, Texas.
authors.forename: Juan R
authors.initials: JR
authors.lastname: Flores-Gonzalez
authors.affiliation: Department of Surgery, University of Texas Health Science Center at Houston , Houston, Texas.
authors.forename: Jiandi
authors.initials: J
authors.lastname: Mo
authors.affiliation: Department of Surgery, University of Texas Health Science Center at Houston , Houston, Texas.
authors.forename: Tien C
authors.initials: TC
authors.lastname: Ko
authors.affiliation: Department of Surgery, University of Texas Health Science Center at Houston , Houston, Texas.
authors.forename: Lillian S
authors.initials: LS
authors.lastname: Kao
authors.affiliation: Department of Surgery, University of Texas Health Science Center at Houston , Houston, Texas.
authors.forename: Mike K
authors.initials: MK
authors.lastname: Liang
mesh_terms: D000328:Adult; D005260:Female; D006555:Hernia, Ventral / Q000601:surgery*; D059685:Herniorrhaphy / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013530:Surgical Wound Infection / Q000175:diagnosis* / Q000453:epidemiology*
keywords: incisional hernia; surgical infection; time; ventral hernia