PICO negative pressure wound dressings for closed surgical incisions

Of the 31 studies that provided evidence relevant to the decision problem, 15 were randomised controlled trials and 16 were non-randomised comparative observational studies. The 15 randomised controlled trials were done in secondary or tertiary care and were based on preventing surgical site complications in people with closed surgical incisions who were at high risk of complications after surgery. One was done in the UK. For full details of the clinical evidence, see section 3 of the assessment report.

Of the 15 randomised controlled trials, 8 compared PICO dressings with standard wound dressings in people with closed surgical incisions in Australia, Poland, the UK, Ireland, Japan, Denmark and the US (Chayboyer et al. 2014, Gillespie et al. 2015, Witt-Najchrazak et al. 2015, Karlakki et al. 2016, O'Leary et al. 2016, Uchino et al. 2016, Hyldig et al. 2018 and Galiano et al. 2018 respectively). The studies included a wide range of different types of surgery. The external assessment centre (EAC) considered these studies to have acceptable internal and external validity and to provide relevant evidence on the effectiveness of PICO dressings. Pooled effect estimates from a random-effects meta-analysis of the 8 studies showed a significant reduction in surgical site infection rates in favour of PICO dressings (n=1,804, odds ratio [OR] 0.51, 95% confidence interval [CI] 0.3 to 0.82; p=0.006).

Of the 16 non-randomised comparative observational studies, 10 compared the rates of surgical site infection using PICO dressings with standard wound dressings in people with closed surgical incisions (Adogwa et al. 2014, Matsumoto et al. 2014, Pellino et al. 2014, Pellino et al. 2014b, Selvaggi et al. 2014, Hickson et al. 2015, Fleming et al. 2017, Tan et al. 2017, van der Valk et al. 2017 and Dingemans et al. 2018). The studies included a wide range of different types of surgery. The EAC considered the included observational studies to have acceptable levels of both internal and external validity, and concluded that the evidence was relevant to the decision problem. Pooled effect estimates from a random-effects meta-analysis of the 10 studies showed a significant reduction in surgical site infection rates in favour of PICO dressings (n=2,669, OR 0.27, 95% CI 0.14 to 0.53; p=0.001). However, the EAC noted that the observational studies may overestimate the clinical benefits of PICO dressings because of potential selection and publication bias.

Two of the randomised controlled trials and 5 of the observational studies also reported rates of seromas in people with closed surgical incisions. Pooled effect estimates from a random-effects meta-analysis of these 7 studies showed a significant reduction in the incidence of seromas in favour of PICO dressings in a range of different types of surgery (n=771, OR 0.19, 95% CI 0.08 to 0.47; p=0.0003). The EAC noted that this reduction in seroma rates was mainly driven by the observational study results.

The included studies considered the use of PICO dressings for 6 different types of surgery:

• orthopaedic surgery (2 randomised controlled trials and 3 observational studies, n=607)

• colorectal surgery (1 randomised controlled trial and 4 observational studies, n=209)

• obstetric surgery (2 randomised controlled trials and 1 observational study, n=2,911)

• plastic/breast surgery (1 randomised controlled trial and 1 observational study, n=420)

• vascular surgery (2 observational studies, n=193)

• cardiothoracic surgery (1 randomised controlled trial, n=80).
  
  Analyses by surgery type showed that reductions in the rate of surgical site infection rates with PICO varied across different types of surgery: the reductions were only significant in obstetric surgery (OR 0.48, 95% CI 0.30 to 0.76; p=0.002) and orthopaedic surgery (OR 0.45, 95% CI 0.22 to 0.91; p=0.03).

The EAC noted the clinical and statistical heterogeneity of the studies that were included in the meta-analyses. There was wide variation in the risk characteristics of the populations, the definition of surgical site infections, how long the dressing was in place, and the length and frequency of follow up. The analyses based on surgery type also included relatively few studies. Nonetheless, the random-effects meta-analyses included a relatively large number of study populations and the EAC concluded that the results were relevant to the decision problem.

One randomised controlled trial (Karlakki et al. 2016) reported a higher overall rate of blisters in people who had PICO dressings compared with those who had standard wound dressings (11% compared with 1%). The rate of blisters differed considerably between the 3 surgeons who took part in the study. For full details of the adverse events, see section 3.7 of the assessment report.

The company's base-case model showed that 90 days after surgery, PICO dressings are cost saving by around £101 per person compared with standard wound dressings.

The EAC considered that the structure of the company's cost model was adequate for decision making. However, it identified some limitations in the model parameters and made changes to better reflect potential resource use in the NHS. Specifically, the EAC:

• applied baseline incidence rates and the cost of surgical site infections from a UK data source (Jenks et al. 2014)

• calculated the mean cost of surgical site infections by dividing the cost by the number of infections

• updated the number of PICO and comparator dressings used

• used clinical-effectiveness estimates based on the pooled treatment effect from the meta-analysis of the randomised controlled trials.
  
  For full details of the changes and results, see section 4 of the assessment report.

With the EAC's changes, the base-case model showed that 90 days after surgery, PICO dressings are cost saving by around £6 per person compared with standard wound dressings. The main drivers of these savings were the cost of PICO, the likelihood of a surgical site infection, the cost of a surgical site infection and the effectiveness of PICO in reducing the incidence of surgical site infections. The analyses by surgery type showed that PICO was cost saving for colorectal, cardiothoracic and vascular surgery, but was not cost saving for orthopaedic, obstetric and plastic/breast surgery. For full details of the cost evidence, see section 4 of the assessment report.