PUBLIC SUMMARY DOCUMENT
Product: SenSura Flex Two-Piece Shallow Convex Baseplate with Adhesive 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(f) of the SAS Schedule, the SenSura Flex Two-Piece Shallow Convex
Baseplate with Adhesive Coupling (SAS code 9890M). The applicant proposed a unit price
inclusive of a price premium over the benchmark unit price for Subgroup 4(f) ($6.930).
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 one of its own products listed in Subgroup 4(f) of the SAS
Schedule, the Easiflex Alterna Two-Piece Convex Baseplate with Adhesive Coupling, as the
comparator. This product is currently listed at the benchmark unit price of $6.930.
3. Background
An application requesting a unit price premium (lower than the unit price premium applied
to this product from 1 July 2011) 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 the removal of the existing price
premium on the basis of insufficient evidence for its justification – a recommendation that
received Cabinet approval in February 2013 and came into effect on 1 April 2013.
4. Clinical Place for the Product
The product is a shallow convex baseplate with an adhesive coupling mechanism suitable
for use as part of a two-piece ostomy appliance system with an adhesive pouch.
5.
SPAP Comment
Clinical Analysis
The Dialogue Study (DK1750S)
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;
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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;
3. 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
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that a) the use of the pre-study appliance was optimised and b) the quality of nursing
advice was constant; and
4. 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, but that only one among them (study DK173OS) presented data pertaining to
the performance of the SenSura Flex Two-Piece Baseplate with Adhesive Coupling versus
an appropriate comparator (though not the comparator nominated by the applicant in the
submission) – the ConvaTec Esteem Synergy Two-Piece Baseplate with Adhesive
Coupling. It is unknown whether the test and reference products were flat or convex.
Study DK173OS, a two-week (one-week per phase), open label, cross-over, randomised
controlled trial involving 46 subjects, had a primary endpoint of patient preference.
Secondary endpoints included flexibility and overall satisfaction. Importantly, patients had
normal peristomal skin at baseline. Several of the results were favourable to the SenSura
product, including 74% patient preference, 69% of patients rating flexibility as good or very
good (versus 24% for the reference product) and more patients rating the SenSura product as
good or very good for security, tack and adhesion by comparison with the reference product.
Overall satisfaction was rated higher for the SenSura product than for the reference product
(6.4/10 versus 5.5/10).
The data from DK173OS, which it was noted cannot be verified as it was available only in
poster form, suggest that the product is at least no worse than its comparator, and may
possibly be better. The 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 of all the data
presented these were the most relevant to the submission and it is detrimental to the
applicant’s case that they were not developed further.
Economic Analysis
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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
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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.
The attributes for which the applicant sought an incremental value based on willingness to
pay in this submission were (the superior performance of the SenSura product in relation to)
skin condition and the related problem of leakage. As previously stated, the Panel
considered the evidence of improved skin condition outcomes due to the use of the SenSura
appliance to be highly confounded. The Panel then noted that the frequency of leakage
reported in the Dialogue Study was likely to be confounded by the nursing effect, even
though it was possible to determine extent. Due again to issues of the quality of clinical
evidence, the Panel considered any value increment to be highly uncertain.
The willingness to pay component of the per unit price premium was calculated per month
(as opposed to per trial period), by dividing the total value claimed by the maximum
monthly quantity of products subsidised under the SAS. The Panel noted that this method
of distributing the aggregate price premium requested across a quantity units based on SAS
maximum quantity thresholds, as was applied in all three components of the applicant’s
economic case, resulted in the applicant’s requesting widely varying unit price premiums for
the same feature across multiple submissions – the greatest being for products subject to the
lowest maximum monthly quantities. In a context in which the SPAP has previously
recommended absolute unit price premiums for features demonstrated to improve health
outcomes, it was noted that this methodology was inappropriate.
Financial Analysis
Not undertaken.
Overarching Summary of SPAP Position
The evidence supporting superiority of the product over a relevant comparator is weak and
the economic model is based on a study which is likely to be highly confounded.
The application relies heavily on the Dialogue Study with regard to skin improvement and
related cost offsets, decreased accessory use and a willingness to pay. This study is not
suitable to be used in a comparative evaluation because of the single arm design. The
assumption that the only difference between the ‘before’ and ‘after’ states is the nature of
the appliance is highly problematic. The applicant has discounted the premium requested as
an attempt to address these issues. The outcomes are however highly uncertain and are not
addressed through a discounting approach.
Reliance on the Dialogue Study to support the claim for a price premium has not assisted
this submission. The study is not considered to be informative to decision making and the
Panel determined that the Dialogue Study will not be accepted in any future price premium
applications submitted for the consideration of the SPAP.
There is evidence presented in study DK173OS, a head-to-head trial of the SenSura product
with reference to an appropriate comparator, of a patient preference favouring the SenSura
product. However interpretation of the available data is limited by the nature of the study,
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no detailed data were presented to support the case for a premium and the applicant has not
attempted to develop an economic argument based these data.
The evidence provided within the current submission is inadequate to support the granting
of a price premium over the benchmark-priced products in the subgroup.
An application based on DK173OS could be considered by the applicant, but it was
acknowledged that the study design and the subjective nature of the outcome measures
would constitute limitations.
6. SPAP Recommendation
The SPAP recommended that the applicant’s request for the application of a unit price
premium to the SenSura Flex Two-Piece Shallow Convex Baseplate with Adhesive
Coupling, currently listed in Subgroup 4(f) of the SAS Schedule, be rejected due to an
inadequate evidence base in support of the claim of product superiority.
7. Context for Decision
The SPAP helps decide whether stoma products should be subsidised and, if so, the
conditions of their subsidisation in Australia. It considers submissions in this context. An
SPAP decision not to recommend listing or not to recommend changes to a listing does not
represent a final SPAP view about the merits of a particular stoma product. A company can
resubmit to the SPAP following a decision not to recommend listing or changes to a listing.
The SPAP is an advisory committee and as such its recommendations are non-binding on
Government. All SPAP recommendations are subject to Cabinet/Ministerial approval.
8. Applicant’s Comment
There were no comments provided in relation to the SPAP recommendation.
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