Negative pressure wound therapy versus usual care for surgical wounds healing by secondary intention (SWHSI-2 trial): study protocol for a pragmatic, multicentre, cross surgical specialty, randomised controlled trial.

Background: The majority of surgical wounds are closed (for example with sutures or staples) and so heal by primary intention. Where closure is not possible, or the wound subsequently breaks down, wounds may be left to heal from the bottom up (healing by secondary intention). Surgical wound healing by secondary intention (SWHSI) frequently presents a significant management challenge. Additional treatments are often required during the course of healing, and thus a significant financial burden is associated with treating these wounds. Increasingly, negative pressure wound therapy (NPWT) is used in the management of SWHSI. This wound dressing system provides a negative pressure (vacuum) to the wound, removing fluid into a canister, which is believed to be conducive to wound healing. Despite the increasing use of NPWT, there is limited robust evidence for the effectiveness of this device. A well-designed and conducted randomised controlled trial is now required to ascertain if NPWT is a clinically and cost-effective treatment for SWHSI.

Methods: SWHSI-2 is a pragmatic, multi-centre, cross surgical specialty, two arm, parallel group, randomised controlled superiority trial. Adult patients with a SWHSI will be randomised to receive either NPWT or usual care (no NPWT) and will be followed up for 12 months. The primary outcome will be time to healing (defined as full epithelial cover in absence of a scab) in number of days since randomisation. Secondary outcomes will include key clinical events (hospital admission or discharge, treatment status, reoperation, amputation, antibiotic use and death), wound infection, wound pain, health-related quality of life, health utility and resource use.

Discussion: Given the increasing use of NPWT, despite limited high-quality supporting evidence, the SWHSI-2 Trial will provide robust evidence on the clinical and cost-effectiveness of NPWT in the management of SWHSI. The SWHSI-2 Trial opened to recruitment in May 2019 and is currently recruiting across 20 participating centres.

Trial Registration: ISRCTN 26277546 . Prospectively registered on 25 March 2019.