PICO negative pressure wound dressings for closed surgical incisions

The committee noted considerable evidence to show the effectiveness of PICO in reducing rates of surgical site infections (18 studies) and seromas (7 studies). The company did meta-analyses using a fixed-effect model, whereas the external assessment centre (EAC) used a random-effects model. The committee considered that the EAC's approach was more appropriate because of the wide variation in the study populations, interventions and the definitions of surgical site infections. The committee concluded that there was convincing evidence that using PICO dressings reduces surgical site infections and seromas in people with closed surgical incisions. The committee considered that there was less certainty about how PICO dressings affect other surgical site complications (such as wound dehiscence, haematoma, delayed healing or excessive scarring) because of the small number of studies in the analyses.

The experts advised that careful patient selection was important when using PICO dressings. The committee noted that the included studies only recruited people who were considered to be at high risk of developing surgical site complications, but that many of the studies did not explicitly state the definition of high risk. The experts advised that there were a number of factors associated with an increased risk of surgical site complications, including age, obesity, cigarette smoking and diabetes. There are also several surgical situations that increase the risk, such as repeat operations and the need for emergency surgery. The committee noted that section 3 of a NICE evidence review for NICE's 2008 guideline on preventing and treating surgical site infections identified the main risk factors for surgical site infections as age, underlying illness, obesity, smoking, wound classification, and site and complexity of procedure. It concluded that healthcare professionals should take these factors into account when considering whether to use PICO dressings.

The committee noted that PICO is intended for closed surgical incisions in which the amount of exudate was anticipated to be low or moderate. The clinical experts advised that PICO dressings should be used for closed surgical incisions that are unlikely to need multiple dressing changes. Large amounts of exudate may lead to multiple dressing changes being needed, so PICO dressings should not be used for these types of wounds.

The committee noted that the published evidence included the use of PICO dressings in 6 different types of surgery, and that the meta-analysis identified a statistically significant reduction in the risk of surgical site infections when it was used in orthopaedic and obstetric surgery. The committee concluded that the type of surgery was an important factor in selecting people for PICO dressings, and that it should be considered in the overall risk assessment for post-operative complications. However, the committee considered that the evidence was too limited to make recommendations on the use of PICO dressings by surgery type.

The committee noted that adverse events were rare in the studies but that skin blisters and maceration may occur when using PICO dressings. A clinical expert advised that skin blisters may develop because of skin tension, which is likely to be the result of the dressing being stretched over the wound. This was corroborated by the results of 1 study, in which the highest incidence of skin blisters was in people whose dressings were applied by trainee staff.

The company stated that there had been around 147 reported cases of the PICO pump failing since its launch in 2007. The committee considered that pump failure would incur additional costs, including application of additional dressings and pump replacement, but it acknowledged that the reported rates of pump failure were very low.

The committee noted that only a small number of the studies included NHS settings; for example, only 1 of the randomised controlled trials was done in the UK. However, 9 of the studies included in the meta-analyses were done in European countries including Ireland, Italy, the Netherlands, Denmark and Poland. A clinical expert stated that PICO dressings are widely used across Europe and that both population demographics and the fundamentals of wound therapy were likely to be similar across Europe. The committee concluded that the evidence for PICO dressings was broadly generalisable to the NHS.

The committee noted that since the technology was notified to NICE, newer versions of PICO dressings have been developed. The latest version available to the NHS is the PICO7 system. The company confirmed that the PICO7 has an improved pump design and belt clip but that the functional mechanism of the dressings remains the same. The committee considered that the evidence on which it evaluated PICO dressings was generalisable to the PICO7 system.

The clinical experts advised that training was an important consideration in the use of PICO dressings. Maintaining a seal is integral to the continued effectiveness of negative pressure, but in creating the seal it is important to ensure that the skin is not placed under excessive tension. The experts also described certain situations in which applying the dressing was awkward (such as on the lower abdomen after a caesarean section or over bony protrusions, especially if there is excessive moisture). The experts also stated that training is important for healthcare staff who provide post-operative care both in hospital and in the community. They emphasised that a lack of knowledge may lead to dressings being removed too early, or to unnecessary dressing changes that are likely to negatively affect clinical outcomes and costs. The committee concluded that training was important in realising the benefits of PICO dressings.

The committee noted the EAC's changes to the company's cost model (see section 3.9) and agreed that the updated model better reflected cost and resource use in the NHS. The committee considered the numbers of PICO dressings and standard dressings that were likely to be needed per person, and the importance of length of stay in hospital in determining cost calculations. It noted that the instructions for use suggest that 1 PICO kit (1 pump and 2 dressings) will last for up to 7 days after surgery. However, the clinical experts indicated that the number of dressings used and the length of stay vary widely depending on the type of surgery. The EAC explained that its calculations were based on the use of 1.09 PICO dressings per person with an average of 5.3 days' stay in hospital. It also estimated the number of PICO dressings used by surgery type; for example, it estimated 1.81 PICO dressings used for colorectal surgery and 1.58 used for vascular surgery. The committee concluded that although it agreed with the EAC's approach to cost modelling, there were uncertainties because of the differences in the populations considered.

The committee noted how the rate and cost of surgical site infections affected the outcomes of the cost modelling. Having seen convincing evidence to support a reduction in the rate of surgical site infections with PICO dressings, the committee concluded it was plausible that the additional cost of PICO dressings compared with standard wound dressings would be offset by a reduction in the overall costs associated with treating surgical site infections.

The EAC did sensitivity analyses, which showed that the cost model was most sensitive to the purchase cost of PICO dressings and their effectiveness in reducing surgical site infections.

The committee noted that neither the company's original model nor the EAC's updated model included staff costs associated with applying PICO and standard wound dressings. Although applying a PICO dressing could take an additional 1 or 2 minutes compared with applying a standard wound dressing, a clinical expert noted that for appropriately trained staff any additional time was negligible.

The committee recalled the EAC's updated cost model, which suggested that PICO dressings are cost saving by around £6 per person (although the cost saving may vary by type of surgery). Overall, the committee concluded that PICO dressings are likely to provide extra clinical benefits at a similar overall cost compared with standard wound dressings.