Clinical and cost-effectiveness of negative pressure wound therapy versus usual care for surgical wounds healing by secondary intention: the SWHSI 2 pragmatic RCT.

Abstract

Surgical wounds healing by secondary intention occur if a surgical wound is not closed or dehisces following primary closure. Surgical wounds healing by secondary intention are common and adversely affect patients' quality of life. Treatment is often prolonged, complex and expensive. Negative pressure wound therapy applies a controlled vacuum to the wound and is increasingly used to promote surgical wound healing by secondary intention despite limited rigorous evidence for the clinical and cost-effectiveness of negative pressure wound therapy to augment surgical wound healing by secondary intention. Assess the clinical and cost-effectiveness of negative pressure wound therapy versus usual care (no negative pressure wound therapy) in treating surgical wounds healing by secondary intention. A pragmatic, two-arm, parallel-group, randomised controlled superiority trial. Twenty-eight UK NHS Trusts randomised adult patients with a surgical wounds healing by secondary intention to receive negative pressure wound therapy or usual care (no negative pressure wound therapy). The planned sample size was 696 participants. Participants were followed up for 12 months via weekly telephone contact to collect the primary outcome (time to healing: full cover with no scab in days since randomisation) and clinical secondary outcomes: wound healing, surgical site infection, pain, hospital re-admission, current treatment and reasons for treatment change (if applicable), reoperation, amputation, antibiotic use, death. Patient-reported outcomes (pain, health-related quality of life and resource use) were collected by postal questionnaire at 3, 6 and 12 months. Validation of the Bluebelle Wound Healing Questionnaire, a patient-reported measure of surgical site infection, was also undertaken. A cost-effectiveness decision model considering all available evidence, and a within-trial cost-utility analysis, was also undertaken to evaluate the cost-effectiveness of negative pressure wound therapy against usual care. Neither participants nor the investigators were blind to treatment allocation. Between 15 May 2019 and 13 January 2023, 686 participants were recruited, randomised and included in the analysis (negative pressure wound therapy <i>n</i>&#x2005;=&#x2005;349; usual care <i>n</i>&#x2005;=&#x2005;337). Most participants had a single surgical wound healing by secondary intention (<i>n</i>&#x2005;=&#x2005;622, 90.7%), located on the foot (<i>n</i>&#x2005;=&#x2005;551, 80.3%) or leg (<i>n</i>&#x2005;=&#x2005;69, 10.1%) arising following vascular surgery (<i>n</i>&#x2005;=&#x2005;619, 90.2%). Most participants had comorbidities; diabetes (<i>n</i>&#x2005;=&#x2005;549, 80.0%), cardiovascular disease (<i>n</i>&#x2005;=&#x2005;446, 65.0%) and/or peripheral vascular disease (<i>n</i>&#x2005;=&#x2005;349, 50.9%). Median time to healing was 187 days (negative pressure wound therapy) versus 195 days (usual care), with no evidence that negative pressure wound therapy reduced the time to wound healing compared to usual care (hazard ratio 1.08, 95% CI 0.88 to 1.32; <i>p</i>&#x2005;=&#x2005;0.47). Odds of re-admission, reoperation, surgical site infection and antibiotic use were slightly higher, and odds of amputation or death slightly lower for negative pressure wound therapy participants. These results were not clinically or statistically significant. Bluebelle Wound Healing Questionnaire, quality of life and wound pain scores were not statistically significantly different at any time point. Serious adverse events were rare (nine negative pressure wound therapy vs. five usual-care participants). Both cost-effectiveness analyses concluded that negative pressure wound therapy generates higher costs and marginally higher quality-adjusted life-years than usual care, although findings were statistically insignificant. The probability of negative pressure wound therapy being cost-effective was under the recommended National Institute for Health and Care Excellence cost-effectiveness thresholds. The Bluebelle Wound Healing Questionnaire was acceptable to participants, had low levels of missing data and demonstrated good levels of sensitivity and specificity in the detection of surgical site infection in surgical wounds healing by secondary intention. The trial included a high proportion of diabetic participants with foot wounds, which may affect study generalisability. Negative pressure wound therapy use for 'wound management', common in certain surgical specialties, was not assessed in this study. Negative pressure wound therapy is not clinically or cost-effective in augmenting healing in patients with surgical wounds healing by secondary intention, particularly those with comorbidities. Evaluation of methods to treat or prevent infection of surgical wounds healing by secondary intention and evaluation of negative pressure wound therapy for 'wound management' are recommended. This synopsis presents independent research funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme as award number 17/42/94. After an operation, most wounds are closed using stitches or staples. Some wounds cannot be closed and are left open. Some closed wounds may reopen. These &#x2018;open&#x2019; wounds are usually left to heal slowly from the bottom up. Negative pressure wound therapy is commonly used to treat &#x2018;open&#x2019; wounds. Negative pressure wound therapy uses a machine to apply gentle suction to a wound, which removes wound fluid, and may help keep the wound clean and perhaps aid healing. We do not know if negative pressure wound therapy is as good as, better than or worse than standard wound dressings that are also used for healing &#x2018;open&#x2019; surgical wounds. We also do not know if negative pressure wound therapy is good value for money. There has not been enough, high quality, independent research to enable doctors and nurses to decide on the best treatment. Between May 2019 and January 2023, 686 patients with an open wound agreed to take part and were equally randomly assigned to standard dressings or negative pressure wound therapy. Most of the wounds were on patient&#x2019;s feet. Most patients had diabetes, and many patients also had conditions affecting their heart and/or blood vessels. We collected wound healing data, treatment information and health outcomes for each participant for a year. We found no clear evidence that negative pressure wound therapy provided any significant benefits for patients and specifically that negative pressure wound therapy did not reduce the time it took for wounds to heal compared to standard wound care. Negative pressure wound therapy was also more expensive than standard dressings and so was not likely to be a good use of healthcare resources. Patients and doctors will be able to make more informed decisions about which dressing to use to help wounds heal. The National Health Service can save money by recommending the use of standard dressings for open wounds instead of using the more expensive negative pressure wound therapy.