Goligher 1975.

Methods	RCT Methods to control for contributory patient factors: none
Participants	Age: Group 1: < 60 years 66.4%, 60‐80 years 31.8%, > 80 years 1.9% Group 2: < 60 years 64.5%, 60‐80 years 33.6%, > 80 years 1.9% Group 3: < 60 years 61.8%, 60‐80 years 35.5%, > 80 years 2.7% Gender: Group 1: 45.8% female Group 2: 32.7% female Group 3: 46.3% female Type of incision: all paramedian incisions Type of surgery: all elective procedures Group 1: peptic ulcer disease 37.3%, colorectal cancer 18.7%, palliative 8.4%, inflammatory bowel disease 22.4%, other 13.1% Group 2: peptic ulcer disease 32.7%, colorectal cancer 23.3%, palliative 6.5%, inflammatory bowel disease 23.3%, other 14.0% Group 3: peptic ulcer disease 36.4%, colorectal cancer 17.2%, palliative 10.0%, inflammatory bowel disease 21.8%, other 14.5% Contamination classification of included participants: Group 1: contaminated 21.5% Group 2: contaminated 30.8% Group 3: contaminated 18.2% Pre‐operative antibiotic use: not described Prognostic patient factors: Group 1: obesity 30.8%, malignancy 27.1%, corticosteroids 8.4% Group 2: obesity 35.5%, malignancy 30.0%, corticosteroids 12.1% Group 3: obesity 40.0%, malignancy 27.3%, corticosteroids 10.0% Inclusion criteria: patients undergoing elective laparotomy through rectus‐displacing paramedian incisions Exclusion criteria: none described
Interventions	Comparisons reported: Group 1 Suture: chromic catgut (monofilament, fast absorbable) Suturing technique: continuous, plus reinforcing interrupted sutures on the anterior rectus Closure method: layered Group 2: Sutures: chromic catgut (monofilament, fast absorbable) plus nylon retention sutures Suture technique: continuous, plus reinforcing interrupted nylon sutures on the anterior rectus Closure method: layered Group 3: Suture: stainless steel (monofilament, non‐absorbable) Suturing technique: interrupted, "figure‐of‐8" sutures Closure method: mass Surgeon characteristics: Group 1: consultant 30.0%, registrar 70.0% Group 2: consultant 30.8%, registrar 66.3%, unknown 2.8% Group 3: consultant 38.2%, registrar 60.0%, unknown 1.8%
Outcomes	Incisional hernia: not defined Follow‐up duration: 6 months Wound infection: not defined Dehiscence: not defined Sinus or fistula: "Persistent wound infection and sinus formation"
Notes	Hernia data excluded, due to < 1 year's follow‐up Group 2 excluded from analysis (combined absorbable and non‐absorbable sutures)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Not described
Incomplete outcome data (attrition bias) All outcomes	Low risk	Participants followed up for < 1 year for incisional hernia outcomes
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