title: A call for a standardized definition of perforated appendicitis.
abstract: BACKGROUND
  Abscess rates have been reported to be as low as 1% and as high as 50% following perforated appendicitis (PA). This range may be because of lack of universal definition for PA. An evidence-based definition (EBD) is crucial for accurate wound classification, risk-stratification, and subsequent process optimization. ACS NSQIP-Pediatric guidelines do not specify a definition of PA. We hypothesize that reported postoperative abscess rates underrepresent true incidence, as they may include low-risk cases in final calculations.
  
  
  METHODS
  Local institutional records of PA patients were reviewed to calculate the postoperative abscess rate. The ACS NSQIP-Pediatric participant use file (PUF) was used to determine cross-institutional postoperative abscess rates. A PubMed literature review was performed to identify trials reporting PA abscess rates, and definitions and rates were recorded.
  
  
  RESULTS
  20.9% of our patients with PA developed a postoperative abscess. The ACS NSQIP-Pediatric abscess rate was significantly lower (7.61%, p<0.001). In the eighteen published studies analyzed, average abscess rate (14.49%) was significantly higher than ACS NSQIP-Pediatric (p<0.001). There was significantly more variation in trials that do not employ an EBD of perforation (Levene's test F-value =6.980, p=0.018).
  
  
  CONCLUSIONS
  A standard EBD of perforation leads to lower variability in reported postoperative abscess rates following PA. Nonstandard definitions may be significantly altering the aggregate rate of postoperative abscess formation. We advocate for adoption of a standard definition by all institutions participating in ACS NSQIP-Pediatric data submission.
  
  
  METHODS
  III.
authors.affiliation: Division of Pediatric Surgery, Department of Surgery, University Of Wisconsin School of Medicine and Public Health; University of Wisconsin Hospital and Clinics, American Family Children's Hospital, Madison, WI, USA; Molecular and Applied Nutrition Training Program, University of Wisconsin-Madison, Madison, WI. Electronic address: rogers@surgery.wisc.edu.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Rogers
authors.affiliation: Division of Pediatric Surgery, Department of Surgery, University Of Wisconsin School of Medicine and Public Health; University of Wisconsin Hospital and Clinics, American Family Children's Hospital, Madison, WI, USA.
authors.forename: Tiffany J
authors.initials: TJ
authors.lastname: Zens
authors.affiliation: Division of Pediatric Surgery, Department of Surgery, University Of Wisconsin School of Medicine and Public Health; University of Wisconsin Hospital and Clinics, American Family Children's Hospital, Madison, WI, USA.
authors.forename: Charles M
authors.initials: CM
authors.lastname: Leys
authors.affiliation: Division of Pediatric Surgery, Department of Surgery, University Of Wisconsin School of Medicine and Public Health; University of Wisconsin Hospital and Clinics, American Family Children's Hospital, Madison, WI, USA.
authors.forename: Peter F
authors.initials: PF
authors.lastname: Nichol
authors.affiliation: Division of Pediatric Surgery, Department of Surgery, University Of Wisconsin School of Medicine and Public Health; University of Wisconsin Hospital and Clinics, American Family Children's Hospital, Madison, WI, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Ostlie
mesh_terms: D018784:Abdominal Abscess / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D000208:Acute Disease; D001062:Appendectomy; D001064:Appendicitis / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D002648:Child; D006801:Humans; D015994:Incidence; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D017410:Practice Guidelines as Topic
keywords: Abscess; Evidence-based; NSQIP; Perforated appendicitis; Wound classification