NICE commissioned an external assessment centre (EAC) to review the evidence submitted by the company. This section summarises that review. Full details of all the evidence are in the project documents on the NICE website.
3.1 Twenty studies were relevant to the decision problem in the scope:
2 comparative studies (Schiffmann et al. 2019, Wasmann et al. 2019)
4 prospective studies (Jiménez Rodríguez et al. 2018, Milito et al. 2017, Rottoli et al. 2018, Strangio et al. 2015)
14 retrospective studies (Arezzo et al. 2015, Boschetti et al. 2018, Huisman et al. 2019, Katz et al. 2018, Keskin et al. 2015, Kuehn et al. 2016, Manta et al. 2016, Mussetto et al. 2017, Nerup et al. 2013, Riss et al. 2010, Riss et al. 2009, Srinivasamurthy et al. 2013, van Koperen et al. 2009, Weidenhagen et al. 2008).
Three abstracts of non-comparative studies were also included (DiMitri et al. 2010, Martel et al. 2013, and McAuley et al. 2013). Three studies were in the UK.
3.2 The EAC considered the quality of the evidence for Endo-SPONGE to be very low. It found a high risk of bias because of the retrospective study design and small sample sizes (ranging from 3 to 34 people). It noted the clinical heterogeneity related to population characteristics and the definition of surgical site infections and success. It also found inconsistencies in how long Endo‑SPONGE was in place and how many times it was changed, the length and frequency of follow up and concurrent or additional treatments. This might reflect the clinical uncertainty and variation in practice when treating anastomotic leaks. The clinical experts suggested that there is no clearly defined care pathway, and treatment is based on several factors. These include the patient's overall condition, the anastomotic defect size and location, the indication for primary resection and the presence of a proximal stoma.
3.3 The available evidence suggests that Endo‑SPONGE could be a treatment option for anastomotic leak. The success rate of cavity closure for Endo‑SPONGE was about 85% and ranged from 40% to 100%, but the definition of success varied across studies. The stoma reversal rate after successful Endo‑SPONGE treatment was about 77%, ranging from 38.5% to 92.3%. One study reported that 6 out of 8 patients would be willing to have Endo‑SPONGE treatment again if needed.
3.4 The company presented a de novo cost analysis with an Endo‑SPONGE decision tree and a comparator decision tree. Each decision tree had 4 branches for different grades of anastomotic leak that may result in non-surgical or surgical treatment. The company noted that its cost model structure was based on the grades referred to in The Association of Coloproctology of Great Britain and Ireland's (ACPGBI) guidance on the prevention, diagnosis and management of colorectal anastomotic leakage. The results from the company model estimated that Endo‑SPONGE was cost saving by £2,419.50 per person in the first year.
3.5 The EAC noted that there was no standard treatment pathway for managing anastomotic leak. The procedure cost varied by care setting (inpatient or outpatient), types of sedation (general or local anaesthetic) and whether or not it was combined with other interventions. The EAC proposed 3 scenarios based on available evidence and expert advice to explore the cost impact in clinical practice.
The EAC has revised key clinical parameters based on published data but also uses clinical parameters from the company submission
3.6 The EAC considered the company model structure, a 1‑year cycle and a 10‑year time horizon to be appropriate. It changed some of the clinical and cost parameters based on published studies and expert advice and focused on percutaneous drainage as a comparator. However, it acknowledged that there was uncertainty about the most appropriate clinical inputs to the model because there was no clearly defined care pathway. Because of the uncertainty in the clinical parameters, the EAC also used the company clinical values in the scenario analyses.
3.7 The EAC noted that the cost impact of Endo‑SPONGE compared with percutaneous drainage varied depending on the scenarios and clinical parameters considered. One scenario was based on Endo‑SPONGE insertion under general anaesthesia in theatre, with subsequent sponge changes in an outpatient setting such as an endoscopy suite. Using the company's clinical parameters in the model, this scenario estimated that Endo‑SPONGE would save £726 per person in the first year. Using the EAC's alternative clinical inputs in the model, Endo‑SPONGE was estimated to have an additional cost of £1,141 per person in the first year. If both the insertion and replacement procedures were done in an operating theatre under general anaesthesia, then Endo‑SPONGE was cost incurring in the first year.
3.8 The EAC model estimated that Endo‑SPONGE was cost saving over a 10‑year time horizon. This was when the insertion procedure was done in an operating theatre and sponge changes were done in an endoscopy suite or day-case theatre under light sedation. Using the company's or EAC's clinical parameters, this results in cost savings of £2,829.30 and £68.20 per person at 10 years, respectively, compared with percutaneous drainage.
3.9 In response to the committee discussion and consultation comments about the draft recommendations, the EAC did additional scenario analyses with alternative comparators. It acknowledged that the treatment pathway is complex and covers a heterogeneous patient population. Also, there is little data available on all the treatment options. The new analyses therefore included comparisons of Endo‑SPONGE with non-surgical interventions including percutaneous drain, trans-anal drain and others that were not specified in the company submission. The results showed that Endo‑SPONGE is cost saving by £298 per person over 1 year compared with a general non-surgical comparator.