NCT01759381.

Study characteristics
Methods	Study design: randomised controlled trial Study grouping: parallel design Ethics and informed consent: not stated Follow‐up period: 3 months Sample size estimate: not reported  ITT analysis: not reported Funding: not reported Preregistration: NCT01759381
Participants	Location: USA Intervention group (NPWT): 11 participants; group 2 (control group): 8 participants; however, this study was terminated earlier and the estimated sample size was unclear Mean age: not reported as mean values Inclusion criteria: >/= 18 years of age; >/= 3 level instrumented thoracic, lumbar, or thoracolumbar spinal fusion Exclusion criteria: < 18 years of age; < 3 level instrumented thoracic, lumbar, or thoracolumbar spinal fusion; spinal infection at time of surgery; history of immunosuppression or chronic systemic infection; pregnancy; inability to provide informed consent.
Interventions	Aim/s: "to evaluate the outcome of incisional negative pressure wound therapy in preventing surgical site infections and wound complications (dehiscence) in high‐risk patients undergoing complex spinal surgery" Group A (NPWT) intervention: NPWT received as opposed to the standard incisional dressing following complex spinal surgery. Group B (control) intervention: no negative pressure wound therapy device; postoperative dressings per the surgeon's standard routine. Study date/s: December 2012 to June 2015
Outcomes	Death Number of participants with postoperative infection Validity of measure/s: not given Time points: 3 months after surgery
Notes	Information is from NCT01759381 registry. This study was terminated earlier and the estimated sample size was unclear. Data were available only for 19 participants.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The allocation of patients (no NPWT device versus applying an NPWT device) will be determined by computer‐generated randomization". Comment: low risk of bias as a proper randomisation method was used.
Allocation concealment (selection bias)	Unclear risk	No information
Blinding of participants and personnel (performance bias) All outcomes	High risk	High risk of bias as NCT01759381 stated this was an open‐label trial.
Blinding of outcome assessment (detection bias) All outcomes	High risk	High risk of bias as NCT01759381 stated this was an open‐label trial.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No information. The trial was terminated earlier and the estimated sample size was unclear.
Selective reporting (reporting bias)	Low risk	All prespecified outcomes were reported in records of NCT01759381.
Other bias	Unclear risk	This study was terminated earlier and it was unclear how the early stopping affected the study results.