Brolin 1996.

Methods	RCT Methods to control for contributory patient factors: none described
Participants	Age: Group 1 (mean): 39 years Group 2 (mean): 38 years Gender: Group 1: 81.6% female Group 2: 80.0% female Type of incision: all participants had midline incisions Type of surgery: all were elective bariatric procedures Group 1: vertical banded gastroplasty: 9.2%; Roux‐en‐Y gastric bypass 90.8% Group 2: vertical banded gastroplasty: 11.7%; Roux‐en‐Y gastric bypass 88.3% Contamination classification of included participants: no information provided Pre‐operative antibiotic use: all participants received either a cephalosporin or vancomycin Prognostic patient factors: all participants were morbidly obese Inclusion criteria: participants who had gastric‐restrictive bariatric procedures performed by one surgeon, for treatment of morbid obesity Exclusion criteria: no exclusion criteria were explicitly reported
Interventions	Comparisons reported: Group 1: Suture: polyester (multifilament, non‐absorbable) Suturing technique: continuous Closure method: layered (polyester on fascia, other layers closed by same methods in both groups) Group 2: Suture: PDS (monofilament, slowly absorbable) Suturing technique: interrupted, 'figure‐of‐eight' Closure method: layered (PDS on fascia) Characteristics of surgeons: all procedures were performed by a chief resident
Outcomes	Incisional hernia: participant‐reported symptoms of discomfort or lumps in their incision Follow‐up duration: mean follow‐up was 29.4 months, 65% followed for > 2 years Wound infection: not defined Wound dehiscence: acute dehiscence on the first postoperative day
Notes	Minimum follow‐up period not described; hernias at 1 year not specifically addressed
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	"Randomization was carried out in the operating room according to the last digit of the patient's hospital identification number. Patients with an even number (n = 109) had closure with [Polyester]; patients with an odd digit (n = 120) had closure using [Polydioxanone]."
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	All participants accounted for and included in the analysis
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