PUBLIC SUMMARY DOCUMENT

Product: SenSura Click Two-Piece Shallow Convex Baseplate with Mechanical Coupling

Applicant: Coloplast Pty Ltd

Date of SPAP Meeting: 29-30 July 2013

1.  Proposed Listing on the Stoma Appliance Scheme

The applicant, Coloplast, sought the addition of a price premium to a product currently listed in Subgroup 4(c) of the SAS Schedule, the SenSura Click Two-Piece Shallow Convex Baseplate with Mechanical Coupling (SAS code 9889L). The applicant proposed a unit price inclusive of a price premium over the benchmark unit price for Subgroup 4(c) ($5.839).

The price premium requested was for:

  1. ‘The ability of the SenSura double layer baseplate for improving skin condition and use of accessories.
  2. Abilities of the SenSura appliance to improve aspects related to quality of life, valued by utilisation of willingness-to-pay.’

2.  Comparator

The applicant nominated a Dansac product listed in Subgroup 4(c) of the SAS Schedule, the Nova 2 Two-Piece Convex Baseplate with Mechanical Coupling (SAS code 3867M), as the comparator. This product is currently listed at the benchmark unit price of $5.839.

3.  Background

An application requesting a unit price premium was considered by the Stoma Product Assessment Panel (SPAP) in November 2012 as part of the Group 4 Price Premium Review (SAS 2012-13 Budget measure). At that time the SPAP recommended that the request for a price premium be rejected on the basis of insufficient evidence for its justification.

4.  Clinical Place for the Product

The product is a shallow convex baseplate with a mechanical coupling mechanism suitable for use as part of a two-piece ostomy appliance system with a pouch with a mechanical coupling mechanism.

5.  SPAP Comment

Clinical Analysis

The Dialogue Study (DK175OS)

The Dialogue Study was considered separately by the Panel as it was pivotal to the economic analyses presented by the applicant in all six Coloplast SenSura submissions considered at this meeting. It was a non-comparative, single arm, 6-8 week multi-centre trial conducted across 21 countries in which 3,017 subjects were switched from their current device to an equivalent SenSura product and outcomes before and after were compared.

In the view of the Panel, the following flaws in study design seriously compromised the validity of the evidence provided by the Dialogue Study:

1.  it was non-comparative and single arm in nature;

2.  at the first (inclusion) visit in week one, patients were instructed on the study and the use of SenSura appliances. If it was stated at this visit that the SenSura range of products was likely to offer an improvement, then this could have influenced patient outcomes. Furthermore and in relation to the instruction given on the use of the new appliances, 15% of participating patients had never visited a stoma clinic and 53% had only visited when needed. Thus over two thirds of subjects had not had regular clinic visits and discussion by the nurse alone may have significantly improved outcomes. This may have related to a range of activities unrelated to the nature of the device – for example removal, cleansing etc. The extent of the nursing effect was not able to be determined by the Panel due to the non-comparative nature of the trial; and

3.  There was no evidence provided regarding whether or not advice regarding the management of any peristomal skin conditions (PSCs) present at entry was given at visit one. As 60% of patients were deemed by the nurses to have a skin condition at entry and skin disorders did not constitute an exclusion criterion, it seems ethically indefensible that these patients were not provided with advice and/or treatment options – particularly for those patients with a DET score of 4 or more (moderate to severe disease). It was surprising that patients with severe skin conditions (250 or 8% who had an initial DET score of 7 or more) were not excluded from the trial. The Panel considered the question of the ethics of non-intervention in the presence of peristomal skin problems at entry to be critical, and the absence of any information in this regard placed great uncertainty over any impact of the new devices on skin improvement over the study period.

The Panel noted the statistically significant change in the Quality of Life (QoL) metric developed by Pietro (2005) – a mean change from 58.1 to 59.9 (standard deviation 6.9) obtained from the data of 2,672 of the 3017 patients recorded – but was of the view that a difference of 1.8 on a 100-point scale was unlikely to be clinically significant (ie. translate into any meaningful clinical difference in quality of life for patients using SenSura appliances versus prior use products).

The Panel then considered the results based on the peristomal skin assessment tool developed by Coloplast (the DET score) from which the applicant extends an economic analysis. The DET score measures both extent and severity in the three domains of discolouration, erosion and tissue overgrowth, with a maximum score of 15 corresponding to maximum severity. The following issues with DET scoring in the Dialogue Study were identified by the Panel:

  1. The Coloplast Ostomy Skin Tool Handbook gives useful tips to minimise skin irritation etc. and this was presumably part of the advice given to patients at visit one;

2.  There was wide inter-country variation in DET score changes, likely as a result of inter-assessor variability (Jemec et al. 2011). The Panel noted that as was appropriate, initial and final DET scores for individual patients were measured by the same nurse at both visits;

  1. As outlined above in relation to study design, the improvement in DET score is likely to have been influenced by the nature of the nursing intervention in the context of a clinical trial. The applicant attempted to disaggregate the nursing effect from the performance of the appliance by comparing the entry and completion DET scores (and corresponding degree of reduction) of the groups who had never, when needed and regularly visited a stoma clinic, and noting that there was no statistically significant difference between the three groups, thus concluding that nursing effect was not a factor. This method was unconvincing as it relied on the dual assumptions that a) the use of the pre-study appliance was optimised and b) the quality of nursing advice was constant; and
  2. As previously stated, it would have been deemed unethical not to intervene at visit one for those patients with a moderate to severe PSC at entry.

The Panel noted that the applicant’s own submission conveyed that the impact of nursing cannot be differentiated from that of the appliance: ‘the Dialogue Study showed that evidence-based nursing and the use of an appropriate SenSura appliance reduced leakage [leading to PSCs] significantly compared to the pre-study appliance’. Data on file by Aaes states that ‘the possibility of separating the effect of evidence based nursing given at study start and SenSura performance has not been addressed.’

For these reasons, the Panel concluded that the use of the DET score as the primary input into the applicant’s economic model was highly problematic.

Finally, the Panel noted that there was no concrete confirmation provided in either the study report or any of the supplements that any one SenSura product (of the six forming the subjects of the applicant’s current round of submissions) formed part of the Dialogue Study. That any one product was included was instead a matter of assumption. It was the opinion of the Panel that a subgroup analysis, with subgroups defined on the basis of the product used, should have been possible given the large number of overall study participants.

Other Evidence Presented

The Panel noted that the applicant presented numerous other studies in support of its application, none of which presented data pertaining to the performance of the product versus an appropriate comparator from Subgroup 4(a). The most relevant study presented was DK167OS (comparator product ConvaTec Combihesive – a ConvaTec Stomahesive Skin Barrier with a ConvaTec Natura Closed Pouch; test and reference products presumed to be flat).

Study DK167OS, a four-week (two weeks per phase), open label, cross-over, randomised controlled trial involving 63 subjects, had a primary endpoint of patient preference. Secondary endpoints included security, comfort, adhesion, flexibility and skin condition. Importantly, all patients had intact skin at inclusion, with 10% of patients having redness around the stoma. Several of the results were favourable to the SenSura product, including 98% patient preference (likely related to fewer unplanned changes and less ballooning) and superior performance ratings with regard to tack, adhesion, flexibility and ease of removal. Less seepage of effluent was recorded for the test product but no quantification of leakage was provided by the applicant. Peristomal skin condition within 02 cm from the stoma was also significantly improved, but there was no difference observed between the test and reference products at 2-4 cm. The Panel noted that the detail of how skin condition was assessed was not reported in either the poster or article provided and no study report was included in the submission.

This study, the presentation of which was low on the detail of the methodologies used, suggested a potential patient benefit associated with the SenSura product. The open and short-term nature of the trial and the subjective and variable nature of the patient preference outcome measure (which would never be given primacy over the objective measurements which would verify it) constitute limitations, but it was a study relevant to the submission and it is detrimental to the applicant’s case that it was not developed further.

Economic Analysis

The Panel noted that the economic case presented by the applicant in support of the price premium claimed had three main components: a base case model based on the treatment costs associated with PSCs, a reduction in accessory use, and ‘willingness to pay’.

Peristomal Skin Conditions

The PSC arm of the applicant’s economic case used a 15 health state-classification system based on combining five disease types (irritant-contact dermatitis, allergic dermatitis, mechanical trauma, disease-related and infection-related) with three degrees of severity (mild, moderate or severe – classified according to DET score). The difference in the proportion of patients with each type and severity of disease between visits one and two in the Dialogue Study was multiplied by the estimated cost of managing that specific combination of type and severity, then summed for all states and divided by the estimated product usage during the trial period (based on maximum quantity thresholds under the SAS) to calculate the PSC-based component of the per unit price premium.

As outlined above (cf. Clinical Analysis), the use of changes in DET score in the Dialogue Study to underpin this modelling is highly problematic due to likely considerable confounding – ie. stated percentage changes in DET score (the largest in the area of moderate/severe PSCs) cannot be interpreted as being solely due to the performance of the SenSura product. In the view of the Panel, the following additional flaws were inherent in this approach:

  1. The incidence figures were obtained from the applicant’s financial worksheet and could not be verified in the absence of the raw data;
  2. The costs associated with the treatment of mild, moderate and severe disease were derived from a survey of 11 stomal therapy nurses internationally (including one Australian) and it was assumed that the same management algorithms would be applicable to Australia; and
  3. Costs were likely to be inflated particularly with regard to the choice of MBS item for a stoma nurse visit. A visit was costed at $55.85 which is the Medicare scheduled fee for a nurse practitioner visit of greater than 40 minutes duration. This seemed excessive, especially for the management of mild or moderate skin disease. Other assumptions made indicated the likely inflation of modelled treatment costs, including that 100% of cases of moderate/severe PSCs would require treatment with infliximab, and that a proportion of patients would require four nurse and four specialist visits over a seven week period.

Reduction in Accessory Use

The Panel considered the applicant’s calculation of the total premium component due to the reduction in the use of accessories observed in the Dialogue Study (also divided by the number of trial units based on SAS maximum quantity thresholds) to be unsound, given that this would also have been highly influenced by nurse interaction at visit one and was therefore also likely to be highly confounded. It was the opinion of the Panel that if people were using accessories to provide greater protection/security/comfort etc. at study entry, they would be unlikely to change this in the short-term unless it was advised or suggested by nurses that they do so due to a belief that the SenSura product was superior. The Panel noted that this issue was not addressed in the submission.

Willingness to Pay

The Panel noted that the applicant presented two documents supporting willingness to pay – the first an unpublished French study and the other a published and sound discrete-choice experiment by Bonnichsen (2011). The French study reported a willingness to pay among users for the flexibility and comfort, performance with regard to skin condition and leakage, and filter performance of stoma appliances. Bonnichsen reported that respondents had a significant positive willingness to pay for all potential attribute improvements, with the strongest preference being exhibited for a reduction in the incidence of leakage and improvements in system flexibility.