Guidance
3 Evidence
Clinical evidence
Relevant evidence comes from 13 studies, 4 of which are randomised controlled trials
3.1 Of the studies that met the inclusion criteria defined in the scope, 4 were randomised controlled trials (n=1,344) and 9 were non-randomised comparative observational studies (n=1,767). The 4 randomised controlled trials were based on the prevention of sacral pressure ulcers in adults, and none was done in the UK. For full details of the clinical evidence, see section 3 of the assessment report.
Results of the randomised controlled trials are mixed
3.2 The 4 randomised controlled trials (Aloweni et al. 2017, Kalowes et al. 2016, Santamaria et al. 2015a and Walker et al. 2017) compared Mepilex Border Sacrum with standard care in adults at risk of developing pressure ulcers in intensive care units in Singapore, the US and Australia. The external assessment centre (EAC) considered these studies to have acceptable internal and external validity and to provide relevant evidence for the use of Mepilex Border Sacrum. Pooled treatment effect estimates from the fixed-effect meta-analysis of the 3 studies that reported pressure ulcer incidence rates as the number of patients with a pressure ulcer showed a non-significant relative risk (RR) in favour of Mepilex Border Sacrum (RR 0.51, 95% confidence interval [CI] 0.22 to 1.18; p=0.12). Based on the assumption of 1 pressure ulcer per patient in Santamaria (2015a), pooled treatment effect estimates from a fixed-effect meta-analysis of the 4 studies showed a significant relative risk in favour of Mepilex Border Sacrum (RR 0.42, 95% CI 0.20 to 0.86; p=0.02). However, a random-effects meta-analysis of the 4 studies showed a non- significant relative risk with Mepilex Border Sacrum (RR 0.45, 95% CI 0.20 to 1.04; p=0.06).
Evidence from most observational studies is low quality and less relevant
3.3 The EAC considered 3 of the 9 observational studies (Park 2014, Richard-Denis et al. 2017a and Santamaria et al. 2015b) to have acceptable levels of both internal and external validity. However, the observational studies overall had lower internal and external validity compared with the randomised controlled trials, because of unacceptable cohort recruitment, inconsistencies in describing procedures and measurements, and unclear presentation and precision of results. Because of this, the EAC concluded that the evidence from the 9 observational studies was less relevant to the decision problem.
There is less evidence for Mepilex Border Heel
3.4 The EAC noted that the clinical effectiveness of Mepilex Border Heel is uncertain because of the limited comparative evidence. Only 2 observational studies assessing the heel dressing were identified (Haisley et al. 2015 and Santamaria et al. 2015b), and only the Santamaria study had acceptable levels of internal and external validity. This study (n=412) showed a significant difference in the proportion of patients who developed a pressure ulcer, in favour of Mepilex Border Heel (p=<0.001).
Cost evidence
The company's cost model shows that the use of Mepilex Border dressings is cost saving
3.5 The company's economic evidence was a cost model comparing standard care for preventing pressure ulcers with standard care and the use of Mepilex Border dressings. The time horizon was less than 1 year. The model was a single-level decision tree comprising health states for 2 possible outcomes, specifically whether or not a patient develops a pressure ulcer. The model assumed that:
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standard care and reductions in pressure ulcer incidence rates were generalisable from Santamaria et al. (2015a) to NHS practice
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resource use was generalisable from Santamaria et al. (2015a) to NHS practice
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the cost of pressure ulcer management in the UK is known and the estimates are reliable
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the costs of implementation and managing adverse events are negligible
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the treatment effect is comparable across different types of Mepilex Border dressing.
The EAC agreed that the structure of the model accurately depicts the patient pathway and any possible changes that may result from the use of Mepilex Border dressings, but it considered that some of the values of the parameters used to populate the model were inappropriate. The company's model showed that using Mepilex Border Heel and Sacrum dressings results in a cost saving of £177 per patient. For full details of the cost evidence, see section 4 of the assessment report.
The EAC's changes to the cost model parameter values make Mepilex Border dressings less cost saving
3.6 The EAC identified limitations in some of the parameter values in the company's model and made changes to better reflect NHS costs, including:
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Applying baseline incidence rates of pressure ulcers from UK sources.
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Calculating the cost of pressure ulcer treatment by appropriately weighting treatment cost for different pressure ulcer stages using UK sources.
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Updating the number of dressing changes and the cost of nursing time.
Clinical-effectiveness estimates in the EAC's model were informed by the pooled treatment effect in the meta-analysis of the 3 randomised controlled trials. These changes to the model decreased the cost savings associated with Mepilex Border Heel and Sacrum dressings to £19 per patient. For full details of the changes, see section 4 of the assessment report.