Canedo 2011.

Study characteristics
Methods	Retrospective cohort study. Study period: 2000 to 2008
Participants	Country: USA. CD patients who underwent intestinal or colorectal resection. Patients who had stoma creation without resection, stoma reversal and lysis of adhesions were excluded
Interventions	1. Preoperative infliximab (n= 65) within 3 months of surgery 2. No preoperative biologics (n= 75)
Outcomes	Wound infection, pulmonary infection, abscess and anastomotic leak within 30 days of surgery
Notes	NOS very high risk of bias overall
Risk of bias
Bias	Authors' judgement	Support for judgement
Representativeness of the exposed cohort	Low risk	Consecutive patients with CD who underwent surgical intestinal and colorectal resection from 2000 to 2008
Selection of the non exposed cohort	Low risk	Both groups obtained from the same hospital and time period
Ascertainment of exposure	Low risk	Retrospective analysis of a prospective surgical database
Demonstration that outcome of interest was not present at start of study	High risk	Firstula/abscess was indication for surgery for 72 patients
Comparability of cohorts (Controlled for critical factor/other medications)	High risk	Did not control for other factors
Comparability of cohorts (Controlled for additional factor)	High risk	Did not control for other factors
Assessment of outcome	Low risk	Retrospective analysis of a prospective surgical database
Was follow‐up long enough for outcomes to occur	Low risk	30 days
Adequacy of follow up of cohorts	Low risk	Patients with incomplete data were excluded