Gillespie 2015.

Methods	Study design: randomised controlled trial Study grouping: parallel Ethics and informed consent: yes Follow‐up period: 6 weeks Sample size estimate: pilot study ITT analysis: yes number randomised: 70 number analysed: 70 Funding: non‐industry Pre‐registration: yes
Participants	Location: Queensland, Australia Intervention group: n = 35control group: n = 35 (primary hip arthroplasty) Mean age: intervention group = 30.6 years (SD 5.5)control group = 30.7 years (SD 5.0) Inclusion criteria: booked for elective caesarean section; pre‐pregnancy BMI ≥ 30; able to provide consent Exclusion criteria: women whose condition changed to require urgent caesarean section; previous participation in the trial; existing infection; unable to speak English
Interventions	Aim/s: to determine the feasibility of conducting a larger trial Primary outcome/s: surgical site infection Secondary outcome/s: type of SSI; wound complications; hospital length of stay; hospital readmission Group 1 (NPWT) intervention: PICO dressing applied over the primarily closed incision by the surgeon in the operating room. On day 5 the dressing was changed to OPSITE Post‐Op Visible. Group 2 (control) intervention: Comfeel dressing reinforced with 2 absorbent dressings, and then with a self adhesive, non‐woven tape, which was applied over the primarily closed incision by the surgeon in the operating room. Participants were discharged with their dressing intact. Study date/s: March 2013 to May 2014
Outcomes	SSI bruising bleeding dehiscence blisters haematoma seroma hospital readmission Cost of dressings Validity of measure/s: CDC definitions and criteria for superficial, deep, and organ/space SSI were used for the primary outcome and SF‐12 for quality of life (QoL reported in the Heard 2017 study). Time points: 30 days and 6 weeks postsurgery
Notes	Investigator contacted for additional details.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "computer generated randomised schedule 1:1 ratio in randomly varying blocks was prepared by the statistician on the research team (not involved in recruitment)"
Allocation concealment (selection bias)	Low risk	Quote: "on skin closure, the RNA opened the next sealed, opaque, numbered envelope"
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Evidence for participants: not possible Comment: unlikely to affect outcomes Evidence for personnel: not possible Comment: unlikely to affect outcomes
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "the independent outcome assessors as well as the data analyst were blinded to group allocation"
Incomplete outcome data (attrition bias) All outcomes	Low risk	An ITT analysis was used.
Selective reporting (reporting bias)	Low risk	Planned outcomes reported. Protocol pre‐registered on ANZCTR.
Other bias	Low risk	None detected.