Guidance
5 Cost considerations
Cost evidence
Published evidence
5.1 The sponsor identified 1 relevant study (Smith and Ingram, 2010). The external assessment centre (EAC) agreed with its inclusion and did not identify any further studies. The study considered the cost effectiveness of Parafricta garments to see if any reduction in treatment costs outweighed the initial item cost. Costs were calculated for each treatment pathway, and it was estimated that Parafricta garments could save more than £63,000 per 100 at‑risk people.
Sponsor's cost model
5.2 The sponsor submitted a de novo cost analysis to assess potential cost savings when using Parafricta Bootees and Undergarments as an adjunct to current clinical care. Full details of all cost evidence and modelling considered by the committee are available in the assessment report overview.
5.3 The sponsor submitted a base‑case analysis for 1 hospital and 1 community setting. The population was people in the community or in hospital who:

had a grade 1 or 2 pressure ulcer and were at risk of progressing to a grade 3 or 4 pressure ulcer

did not have a pressure ulcer but were at risk of developing pressure ulcers caused by friction and shear

had medical conditions in which frail skin is a primary factor and friction and shear could cause skin damage.
Separate analyses were conducted to reflect the garments' use in hospital or in the community. In hospital, potential cost savings were based on expected reductions in length of stay for people using Parafricta garments. In the community, potential cost savings were based on a reduced prevalence rate among those using Parafricta garments. No distinction was made between adults and children, or between the different pressure ulcer grades.
5.4 The sponsor explored the uncertainty around the model parameters and the effect this had on the incremental cost using deterministic and probabilistic sensitivity analyses for both the hospital and community models.
Hospital model
5.5 The sponsor's hospital model base case included several key assumptions. These were as follows:

A time horizon of 1 year.

Five potential pathways for at‑risk people.

The cost of treating people in each of the 5 pathways was calculated by applying the appropriate day costs to the relevant weighted length of stay.

The only additional daily cost for people with a pressure ulcer compared with those without a pressure ulcer was an additional dressing cost of £0.74.

Each person was allocated 6 garments.

Each garment was washed on average twice over the person's length of stay.

Each set of 6 garments was used by an average of 3 different people over the garments' lifetime.
5.6 The base‑case results for the hospital model showed that using Parafricta garments saved £757 per at‑risk person, based on costs of £5,307 per at‑risk person when the garments were not used and £4,550 per at‑risk person when they were. This was based on the cost of each Parafricta garment being £35.14 and an assumed laundry cost of £0.50 per wash, per garment. The weighted median length of stay was 13.7 days for the Parafricta group and 16.2 days for the no Parafricta group. The general hospital costs were £326.53 per day, comprising a bed day cost of £325, a £0.59 per‑day mattress cost and a £0.74 general dressing cost. The additional dressing cost applicable to days with a pressure ulcer was £0.74.
5.7 The results from the sponsor's multi‑way deterministic sensitivity analyses confirmed that the modelled cost savings were most sensitive to the weighted length of stay values used. In these results, Parafricta garments were cost saving in all cases, except when the median weighted length of stay without Parafricta garments was 14.8 days and when the median weighted length of stay with Parafricta garments was 14.9 days. In the sensitivity analysis the cost savings were greatest when the median weighted length of stay without Parafricta garments was 17.7 days and when the median length of stay with Parafricta garments was 12.5 days.
Community model
5.8 The sponsor's community model base case included several key assumptions. These were as follows:

A time horizon of 1 year.

For every person in the community with a pressure ulcer, there were 2 other at‑risk people without a pressure ulcer.

Costs in the community model were based solely on the annual cost of Parafricta garments and the costs associated with nurse visits.

All people with pressure ulcers were assumed to need nurse visits.

The difference between median length of stay when a pressure ulcer developed and time to develop a pressure ulcer was used as a proxy for pressure ulcer duration.

The incidence per at‑risk person and the pressure ulcer duration were used to calculate a point prevalence in Parafricta and no Parafricta groups.
5.9 The base‑case results for the community model showed an annual cost saving of £3,455 per person with a pressure ulcer. The base‑case calculation for treating a person with a pressure ulcer in the community was £5,900, based on 1.86 nurse visits a week at £61 per visit for 52 weeks. Treating a pressure ulcer with Parafricta garments was estimated at £2,445, based on a prevalence ratio of 0.37 and an annual cost of £240 per person with a pressure ulcer.
5.10 Results from the deterministic sensitivity analysis always favoured the use of Parafricta garments and suggested cost savings of approximately £1,500 to £4,500. The lowest cost savings were obtained with a reduction in the effectiveness of Parafricta garments – by increasing the prevalence ratio to 0.685. Results from the probabilistic sensitivity analysis suggested that there is very little uncertainty and that Parafricta garments are always cost saving.
EAC revisions to the hospital cost model
5.11 The EAC did not consider that all of the assumptions in the sponsor's hospital cost model were optimum. The EAC's revisions included a simplified structure based on 3 pathways, which avoided the small patient numbers in some pathways and also calculated mean lengths of stay adjusted with the limited baseline patient characteristics.
5.12 The EAC also amended some of the costs in the model, the most noteworthy of which was the revision of the bed‑day cost. A weighted cost using excess bed‑day cost across a range of wards was used to obtain an estimate of £234 per day. The EAC used a cost of £328 as an upper limit in the sensitivity analysis.
5.13 The revised hospital model base‑case results suggested that use of Parafricta garments saved £595 per at‑risk person. This was based on costs of £3,556 per at‑risk person if Parafricta garments are not used and £2,960 per at‑risk person if the garments are used. In a one‑way sensitivity analysis with a bed day costing £328, the cost savings were increased to £863.
5.14 The EAC also conducted a probabilistic sensitivity analysis which suggested that the use of Parafricta garments resulted in cost savings nearly 80% of the time. Most iterations suggested that Parafricta garments were cost saving, with maximum savings of about £6,000 per at‑risk person. However, there were some iterations in which the garments added costs, reflecting the uncertainty in length of stay data.
EAC revisions to the community cost model
5.15 The EAC recalculated a prevalence ratio based on the adjusted mean length of stay data and obtained a value of 0.53. No other changes were made to the model.
5.16 The base‑case results for the revised community model were estimated at £2,510 per person with a pressure ulcer, based on an unchanged cost per person with a pressure ulcer of £5,900 without Parafricta garments and £3,390 with them. Deterministic sensitivity analysis varying the length of stay data based on lower and upper limits of 95% confidence intervals suggested that the cost savings could be between £2,295 and £2,799.
Committee considerations
5.17 The committee considered that the hospital cost model structure was appropriate and that the sponsor had addressed some of the uncertainties in the cost model through sensitivity analyses. However, it noted that the model included very limited information on the resource implications of having a pressure ulcer, and did not consider pressure ulcer grade. The committee noted that the EAC's revisions simplified the treatment pathways and included weighted mean lengths of stay rather than median values. It considered that analysis based on these revisions was more appropriate, in the context of the data available.
5.18 The committee accepted that the mean length of stay values calculated by the EAC – adjusted to account for differences in patient characteristics between the groups – were appropriate. However, the committee noted that the calculated adjusted mean length of stay values were inconsistent, due to the limited information available on patient characteristics. The committee acknowledged that the relationship between length of stay and pressure ulcer incidence and severity is not straightforward and there are many other factors that can influence length of stay. The committee concluded that further research would be necessary to determine the system impact of using Parafricta Bootees and Undergarments in hospital. It considered that more detailed information on the length of stay, severity of pressure ulcers, the costs of treating them, pressure ulcer status and where a patient is cared for after discharge could be used to inform a more robust cost analysis.
5.19 The committee noted that a very simple approach was adopted for the cost analysis in the community model. It was aware that the only data available were those from the Smith and Ingram (2011) study that was conducted in hospital. The committee considered that the cost savings from the community model were uncertain, but it nevertheless acknowledged the potential for significant cost savings with the use of Parafricta garments in the community if further research demonstrates their effectiveness in reducing the incidence and severity of pressure ulcers in hospital.