Kunitake 2008.

Study characteristics
Methods	Retrospective cohort. Study period: 1993 to 2007
Participants	Country: USA. CD, UC and indeterminate colitis patients who underwent abdominal surgery
Interventions	1. Preoperative infliximab (n= 101) within 12 weeks of surgery 2. No preoperative infliximab (n= 312)
Outcomes	Anastomotic leak, sepsis, intraabdominal abscess, wound infection, wound dehiscence, pneumonia
Notes	NOS very high risk of bias overall Adjusted ORs for preoperative infliximab and c orticosteroids were obtained fr om multivariate regression model.
Risk of bias
Bias	Authors' judgement	Support for judgement
Representativeness of the exposed cohort	Low risk	CD, UC and indeterminate colitis patients who underwent abdominal surgery
Selection of the non exposed cohort	Low risk	Both groups obtained from the same hospital and time period
Ascertainment of exposure	Low risk	Electronic medical records were reviewed
Demonstration that outcome of interest was not present at start of study	High risk	Indication for surgery was intraabdominal abscess in 38 patients
Comparability of cohorts (Controlled for critical factor/other medications)	High risk	Reported event rates
Comparability of cohorts (Controlled for additional factor)	High risk	Reported event rates
Assessment of outcome	Low risk	Electronic medical records were reviewed
Was follow‐up long enough for outcomes to occur	Low risk	30 days
Adequacy of follow up of cohorts	Unclear risk	Information not provided