Cameron 1980.

Methods	RCT Methods to control for contributory patient factors: none described
Participants	Age: not reported Gender: Group 1: 54.5% female Group 2: 51.1% female Type of incision: Group 1: midline 34.1%, paramedian 65.9% Group 2: midline 34.4%, paramedian 65.6% Type of surgery: Group 1: emergency 17.4% Group 2: emergency 22.2% Contamination classification of included participants: Group 1: contaminated 7.2% Group 2: contaminated 10.5% Pre‐operative antibiotic use: no information provided Prognostic patient factors: Group 1: corticosteroid use 1.8%, jaundice 1.2% Group 2: corticosteroid use 1.6%, jaundice 7.2% Inclusion criteria: age > 15 years, with vertical abdominal incisions Exclusion criteria: patients being re‐operated on via an incision made < 1 month previously
Interventions	Comparisons reported: Group 1 Suture: polypropylene (monofilament, non‐absorbable) Suturing technique: interrupted ("figure‐of‐eight, near and far") Closure method: mass Group 2: Sutures: PGA (multifilament, fast absorbable) Suturing technique: interrupted ("figure‐of‐eight, near and far") Closure method: mass Surgeon characteristics: Group 1: consultant/senior resident 56.9%, registrar/senior health officer 43.1% Group 2: consultant/senior resident 56.7%, registrar/senior health officer 43.3%
Outcomes	Incisional hernia: no definition provided Follow‐up duration: 6 months Wound infection: no definition provided Wound dehiscence: complete disruption
Notes	Hernia data not included in analysis due to inadequate follow‐up duration
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method to generate allocation sequence not described ("...randomly allocated...")
Allocation concealment (selection bias)	Low risk	"Patients were randomly allocated to a suture material by the opening of a sealed envelope during the procedure."
Blinding (performance bias and detection bias) All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias) All outcomes	High risk	High loss to follow‐up (33/167 in group 1, 49/180 in group 2)
Selective reporting (reporting bias)	Low risk	There was no evidence of selective reporting
Other bias	Low risk	The study appears to be free of other sources of bias