Predicting Organ Space Surgical Site Infection with a Nomogram

Purpose: We hypothesized that organ space surgical site infections (organ space SSI) are a unique type of surgical site infection and therefore are associated with a unique set of risk factors. The aim of this study was to create a predictive model for organ space SSI after small bowel, colon, or rectal operations. Methods: The 2006 American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) sample (N = 12,373) was used to identify current procedural terminology codes for small bowel, colon, and rectal laparoscopic or open surgical procedures. The following variables were used to build a predictive model of organ space SSI within 30 days post-op: age, gender, body mass index, American Society of Anesthesiologists class, smoking, diabetes, steroid use, 30 days previous radiotherapy or surgery, preoperative serum creatinine and albumin, laparoscopic surgery, wound class, perioperative transfusion, operative time, and surgical site. Patients on chronic mechanical ventilation, dialysis, wound infection, or sepsis preoperatively were excluded. Results: Our organ space SSI model achieved a concordance index of 0.65 when validated in 2007 ACS-NSQIP patients (N = 9,521). A risk calculator designed based upon our model is available at www. clinicriskcalculators. com. Conclusion: This novel and validated nomogram is useful to predict organ space SSI associated with small bowel, colon, and rectal surgical procedures. It may also be useful for risk stratification and risk modification.