Appau 2008.

Study characteristics
Methods	Retrospective cohort. Study period: 1998 to 2007.
Participants	Country: USA. CD patients who underwent ileocolonic resection with anastomosis.
Interventions	1. Preoperative infliximab (n= 60) within 3 months of surgery 2. No preoperative infliximab (n=329)
Outcomes	Wound infection, wound complications, anastomotic leak, sepsis and intraabdominal abscess within 30 days of surgery
Notes	NOS low risk of bias overall A djusted OR s for infliximab, 6MP/azathioprine/ methotrexate, and steroids were obtained from multivariate logistic regression model.
Risk of bias
Bias	Authors' judgement	Support for judgement
Representativeness of the exposed cohort	Low risk	CD database of all patients who underwent ileocolonic resection at the Cleveland Clinic
Selection of the non exposed cohort	Low risk	Both groups obtained from the same hospital and time period
Ascertainment of exposure	Low risk	Medication use verified with pharmacy department and patients were called to confirm last dose of infliximab infusion
Demonstration that outcome of interest was not present at start of study	High risk	Some patient were noted to have intraabdominal abscesses preoperatively
Comparability of cohorts (Controlled for critical factor/other medications)	Low risk	Adjusted for methotrexate, 6‐mercaptopurine, azathioprine, infliximab and steroid use
Comparability of cohorts (Controlled for additional factor)	Low risk	Also adjusted for age, gender, comorbidities, penetrating abscess before surgery, diverting stoma, and disease phenotype
Assessment of outcome	Low risk	Medical charts were reviewed
Was follow‐up long enough for outcomes to occur	Low risk	30 days
Adequacy of follow up of cohorts	Unclear risk	No information was provided