BACKGROUND: Surgical wound healing by secondary intention (SWHSI) presents a substantial management and financial challenge. Negative pressure wound therapy (NPWT) has increasingly been used as a treatment despite an absence of comparative evidence of effectiveness. We evaluated the effectiveness of NPWT compared with usual care for improving time to wound healing in patients with an SWHSI. METHODS: We did a pragmatic, open-label, multicentre, parallel-group, randomised controlled trial in 29 UK National Health Service Trusts. Participants aged 16 years or older with an SWHSI appropriate for both study treatments (NPWT or usual care) were randomly assigned (1:1) by a centralised web-based system. Randomisation was stratified by wound location, wound area, and study centre. Participants were followed up for 12 months. Participants and clinical and research teams could not be masked to treatment. Assessors masked to treatment reviewed wound photography to verify the outcome. The primary outcome was time to wound healing (days from randomisation to complete epithelial cover), analysed via intention to treat using Kaplan-Meier survival curves and a proportional hazards Cox regression model. The trial was registered with ISRCTN, ISRCTN26277546. FINDINGS: Between May 15, 2019, and Jan 13, 2023, 686 participants with an SWHSI were randomly assigned to receive NPWT (n=349) or usual care (n=337). All participants were included in the primary analysis. Most participants were diabetic (n=549, 80·0%) and had a single SWHSI (n=622, 90·7%), located on the foot or leg (n=620, 90·4%), arising after vascular surgery (n=619, 90·2%). There was no clear evidence that NPWT reduced the time to wound healing compared with usual care (hazard ratio 1·08 [95% CI 0·88-1·32], p=0·47). There were 448 adverse events, of which 14 were serious (nine participants in the NPWT group and five participants in the usual care group)
124 were deemed potentially related to treatment. NPWT was found not to be cost-effective compared with usual care. INTERPRETATION: In patients with a lower limb SWHSI, including those with complications of diabetes, there is no clear evidence that NPWT reduced the time to wound healing compared with standard dressings. These findings do not support the use of NPWT to augment SWHSI healing. FUNDING: National Institute for Health Research Health Technology Assessment Programme.