Gainsbury 2011.

Study characteristics
Methods	Retrospective cohort. Study period: 2005 to 2009
Participants	Country: USA. UC patients who underwent ileal pounch‐anal anastomosis
Interventions	1. Preoperative infliximab (n= 29) within 12 weeks of surgery 2. No preoperative infliximab (n= 52)
Outcomes	Pelvic/intraabdominal abscess or wound infection
Notes	NOS low risk of bias overall Adjusted ORs f or preoperative infliximab, 6MP and corticosteroids were obtained from multivariate logistic regression models.
Risk of bias
Bias	Authors' judgement	Support for judgement
Representativeness of the exposed cohort	Low risk	UC patients who underwent ileal pounch‐anal anastomosis from 2005 to 2009
Selection of the non exposed cohort	Low risk	Both groups obtained from the same hospitals and time period
Ascertainment of exposure	Low risk	Medical records were reviewed
Demonstration that outcome of interest was not present at start of study	Unclear risk	No information provided
Comparability of cohorts (Controlled for critical factor/other medications)	Low risk	Adjusted for steroids, 6‐mercaptopurine, and methotrexate
Comparability of cohorts (Controlled for additional factor)	Low risk	Also adjusted for BMI, laproscopic colectomy, and failed medical therapy
Assessment of outcome	Low risk	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	No information provided