Colombo 1997.

Methods	RCT Methods to control for contributory patient factors: none described
Participants	Age: Group 1 (mean): 51.1 years Group 2 (mean): 52.7 years Gender: all participants were female Type of incision: Group 1: lower midline 75%, complete midline 25% Group 2: lower midline 79%, complete midline 21% Type of surgery: Group 1: exploratory laparotomy 51.0%, exploratory laparotomy with bowel resection and anastomosis 13.3%, radical hysterectomy with pelvic lymphadenectomy 23.4%, total hysterectomy 10.1%, pelvic exenteration 2.3% Group 2: exploratory laparotomy 52.6%; exploratory laparotomy with bowel resection and anastomosis 11.1%; radical hysterectomy with pelvic lymphadenectomy 20.3%; total hysterectomy 15.0%; pelvic exenteration 1.0% Contamination classification of included participants: no information provided Pre‐operative antibiotic use: all participants in both groups received pre‐operative antibiotics: 1‐2 doses of intravenous cefazolin for procedures with no bowel resection and cefoxitin, gentamicin and metronidazole for procedures involving bowel resection Prognostic patient factors: all participants in both groups had malignancy Group 1: diabetes 2%, obesity (BMI ≥ 25 kg/m2) 30%, prior chemotherapy 38%, prior radiotherapy 5% Group 2: diabetes 3%, obesity (BMI ≥ 25 kg/m2) 32%, prior chemotherapy 32%, prior radiotherapy 6% Inclusion criteria: all women admitted for surgical treatment of gynaecological cancer using a vertical midline incision Exclusion criteria: none described
Interventions	Comparisons reported: Group 1 Suture: polyglyconate (multifilament, slowly absorbable) Suturing technique: continuous Closure method: mass Group 2: Suture: PGA (multifilament, fast absorbable) Suturing technique: interrupted Closure method: mass Surgeon characteristics: "Most wounds were closed by house officers under the direct supervision of a senior staff gynaecologist..."
Outcomes	Incisional hernia: any palpable defect in the fascia, even if an increase in intra‐abdominal pressure did not result in a swelling in the abdominal scar Follow‐up duration: 12, 24 and 36 months Wound infection: purulent discharge with or without a positive culture Wound dehiscence: no definition provided Suture sinus or fistula: no definition provided
Notes	Hernia data at 12 months used in analysis
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"...according to a table of computer‐generated random numbers..."
Allocation concealment (selection bias)	Low risk	"At the moment of abdominal‐wall suturing, a nurse assigned the patients to one of two closure techniques according to a table of computer‐generated random numbers and informed the surgeons of the type of closure to be used."
Blinding (performance bias and detection bias) All outcomes	Low risk	"Incisions were evaluated using careful palpation by physicians who were unaware of the type of suturing technique."
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants included in analysis. Excluded participants discussed (met exclusion criteria)
Selective reporting (reporting bias)	Low risk	Hernia (at least 1 year); dehiscence and wound infection outcomes all reported
Other bias	Low risk	The study appears to be free of other sources of bias