Efem 1980.

Methods	RCT Methods to control for contributory patient factors: none
Participants	Age: not reported Gender: not reported Types of incisions: all participants underwent a vertical midline incision Types of surgery: Group 1: emergent 45% Group 2: emergent 45% Contamination classification of included participants: not reported Pre‐operative antibiotic use: not reported Prognostic patient factors: not reported Inclusion criteria: patients who underwent procedures through a vertical midline laparotomy Exclusion criteria: paramedian, transverse, oblique, gridiron, Pfannenstiel and Rutherford‐Morrison incisions were excluded
Interventions	Comparisons reported: Group 1 Suture: nylon (monofilament, non‐absorbable) Suturing technique: interrupted, "Figure‐of‐8" Closure method: mass Group 2 Sutures: chromic catgut (monofilament, fast absorbable) and nylon (monofilament, non‐absorbable) Suturing technique: unclear Closure method: layered (#1 chromic for peritoneum, nylon for rectus sheath, 2‐0 chromic for fat) Surgeon characteristics: not reported
Outcomes	Incisional hernia: no definition provided Follow‐up duration: 6‐18 months (80% for 8 months, 10% for 18 months) Wound infection: "Wound sepsis delaying discharge from hospital" Dehiscence: no definition provided Sinus or fistula: no definition provided
Notes	Hernia data excluded from analysis due to inadequate follow‐up duration at 1 year
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	Unclear risk	Unlcear how losses to follow‐up were accounted for
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