Uchino 2013b.

Study characteristics
Methods	Retrospective cohort. 2010 to 2012
Participants	Country: Japan. UC patients who underwent laparotomy. Patients who had subtotal colectomy with mucous fistula before IPAA or ileostomy closure were excluded.
Interventions	1. Preoperative infliximab (n= 22) within 12 weeks of surgery 2. Properative immunomodulators (n= 94) 3. No preoperative infliximab (n= 174) 4. No preoperative immunomodulators (n= 102)
Outcomes	Superficial incisional, deep incisional, organ space surgical site infection, and extraabdominal infections 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	UC patients who underwent laparotomy from 2010 to 2012
Selection of the non exposed cohort	Low risk	Both groups obtained from the same hospital and time period
Ascertainment of exposure	Low risk	Data was obtained from a prospectively maintained database
Demonstration that outcome of interest was not present at start of study	Unclear risk	Included patients with contaminated wounds
Comparability of cohorts (Controlled for critical factor/other medications)	High risk	Univiariate analysis
Comparability of cohorts (Controlled for additional factor)	High risk	Univariate analysis
Assessment of outcome	Low risk	Data was obtained from a prospectively maintained database
Was follow‐up long enough for outcomes to occur	Low risk	30 days
Adequacy of follow up of cohorts	Unclear risk	Information not provided