Sabat 2016.

Methods	Study design: 1:1 parallel‐group randomised controlled trial Study grouping: parallel Ethics and informed consent: yes Sample size estimate: no Follow‐up period: 4 months ITT analysis: no Funding: not stated Pre‐registration: not stated
Participants	Location: Philadelphia, USA Intervention group: n = 33 woundscontrol group: n = 30 wounds (total 49 participants) Mean age: not reported Inclusion criteria: people undergoing open vascular surgery involving a groin incision Exclusion criteria: not stated
Interventions	Aim/s: to compare the effect of postoperative negative pressure therapy to conventional dressings on wound occurrences Group 1 (NPWT) intervention: NPWT device Group 2 control: conventional dressing (gauze and Tegaderm) Study date/s: not stated
Outcomes	SSI wound dehiscence
Notes	Abstract only; unit analysis
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated
Allocation concealment (selection bias)	Unclear risk	Not stated
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	Unclear risk	Not stated
Incomplete outcome data (attrition bias) All outcomes	Low risk	All those recruited appear to have been included in the analysis.
Selective reporting (reporting bias)	Unclear risk	Results for outcomes identified in the methods section were reported. We did not see the original protocol.
Other bias	High risk	Unit analysis