Ohira 2015.

Methods	RCT Methods to control for contributory patient factors: unknown
Participants	Age: not reported Gender: Group 1: female 7.1% Group 2: female 44.4% Types of incisions: all incisions were midline Types of surgery: all elective surgery Group 1: gastric 53.5%; colon 46.5% Group 2: gastric 55.6%; colon 44.4% Contamination classification of included participants: not reported Preoperative antibiotic use: not reported Prognostic patient factors: Group 1: diabetes 10.7%; average BMI 21.7 Group 2: diabetes 25.9%; average BMI 22.0 Inclusion criteria: gastric or colon cancer patients operated on with curative intent, aged 20‐80 years Exclusion criteria: non curative surgery, previous midline incision, laparoscopic surgery; immunosuppression (as defined by long‐term corticosteroid use, uncontrolled diabetes, or cirrhosis of the liver); and the surgeon’s judgment that the patient was unsuitable for the trial.
Interventions	Comparisons reported: Group 1: Sutures: polyglactin (multifilament, fast absorbable) Suture technique: interrupted Closure method: mass closure Group 2: Sutures: PDS (monofilament, slowly absorbable) Suture technique: interrupted Closure method: mass closure
Outcomes	Hernia: physical exam, CT scan every 6 months; follow‐up: up to 36 months (minimum 12 months) Wound Infection: not defined Dehiscence: not defined
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation sequence not clearly described
Allocation concealment (selection bias)	Unclear risk	Allocation concealment not clearly described
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Blinding of outcome assessors not clearly stated
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants accounted for
Selective reporting (reporting bias)	Low risk	There was no evidence of selective reporting
Other bias	High risk	Participants not similar at baseline (higher proportion of women in group 2, 2 vs 12); curative intent of surgery not determined until after randomisation