analysis
Relevant objective
The following objective is addressed in this chapter:
l the appropriate methods for evaluating outcomes for the health economic analysis and resource use.
Method
Appropriate methods were identified from the literature, relevant policy guidelines and with the help of PPI and clinician feedback. Validated health-related quality-of-life (HRQoL) instruments were selected when possible. The resource use questionnaire was developed to facilitate detailed costing of the two treatment arms, from both NHS and societal perspectives.
Results
Health-related quality of life
The wide age range of patients recruited for the study was recognised as a complication from the outset, necessitating the use of multiple instruments and piloting of HRQoL instruments that are not yet widely used in health economics. Furthermore, it was acknowledged that the small sample of patients completing each instrument (i.e. falling into the age range for which each instrument had been validated) would limit full evaluation of these instruments.
In the National Institute for Health and Care Excellence (NICE) reference case, the EuroQol-5 Dimensions (EQ-5D) is specified as the preferred measure of HRQoL in adults.46The EuroQol-5 Dimensions, five-level version (EQ-5D-5L), was therefore chosen as the sole health economics instrument in patients aged ≥17 years. The timing of the data collection would coincide with the release of the value set for the new EQ-5D-5L instrument and it was therefore planned to use corresponding preference values from that publication.47
In the case of assessing HRQoL in children, NICE acknowledges that‘when necessary, consideration should be given to alternative standardised and validated preference-based measures of HRQoL that have been designed specifically for use in children’.46
A 2014 systematic review48of UK economic evaluations of paediatric interventions was critical of published economic evaluations for failing to make use of instruments specifically developed for use with children, and identified the Child Health Utility Index 9D (CHU-9D) as a potentially useful measure for future research. Although CHU-9D had not been used in the economic evaluation studies in this review,
empirical work from the West Midlands (UK) demonstrated the superiority of CHU-9D over the EuroQol-5 Dimensions, Youth (EQ-5D-Y) for children aged 6–7 years, and CHU-9D has been validated for use with children aged 11–17 years.49,50We therefore selected the CHU-9D for use in this study as the sole health economics instrument for patients aged 5–6 years with proxy completion by the parent, for both child and parent/proxy completion for ages 7–10 years and for child completion only in patients aged 11–15 years.
Young people aged 16 years also completed the CHU-9D alongside the EQ-5D-5L. Dual completion by parents and children in the 7–10 years age range presented us with the opportunity to assess whether or not child completion would be feasible as part of a full study.
Although there were initially no plans to include an instrument to assess HRQoL in patients aged<5 years (the question on CHU-9D about‘school work/homework’suggests a natural cut-off point at 5 years as a minimum age in the UK), feedback from clinical colleagues stressed the significant prevalence of burn injuries within younger age groups (the original lower age range for the trial was removed as part of the first amendment, which was submitted to the Research Ethics Committee in September 2014). A decision was therefore taken to introduce the Pediatric Quality of Life Inventory (PedsQL), after the start date of the study, for proxy completion by parents on behalf of children aged 2–4 years. It should be noted that no HRQoL or health economics instrument was identified for ages 0–1 year.
Although there is currently no set of tariff or preference values for PedsQL, we were aware of plans to predict CHU-9D utility values from PedsQL scores using regression mapping algorithms, as part of the National Institute for Health Research (NIHR) Health Technology Assessment (HTA)-funded PREDnisolone in NephrOtic Syndrome (PREDNOS) study (reference number 08/53/31).51It was therefore expected that a mapping algorithm would be in use in time for any full trial of PGT.
Costing/resource use
At the time of preparing the trial protocol, a search of the Database of Instruments for Resource Use Measurement (DIRUM) database (www.dirum.org; accessed 30 January 2014) revealed no previous costing/resource use questionnaires for burn treatments within the disease subcategories of‘wounds’, ‘skin’or‘child health’. A new resource use questionnaire was therefore designed, but drew to some extent on previous work relating to leg ulcers and eczema (seeAppendix 4).52,53
A decision was taken to explore the feasibility of collecting cost data from a societal and a NHS perspective. It was expected that patients in both treatment arms may potentially need to travel long distances to receive care at central locations (particularly those travelling in from more rural areas) and that, outside of the trial environment, if PGT is not received, there may be fewer visits to the clinic. As well as direct travel costs, long journey times may necessitate time off work for both adult patients and parents. It was also expected that those patients not receiving PGT may purchase alternative over-the-counter dressings, bandages, tightly fitting clothing or ointments, hence shifting the cost, to some extent, from the NHS to patient or parent. Based upon feedback from our patient and public representatives, we considered the possibility that if patients deem a pressure garment to offer a degree of protection (versus no pressure garment), they may return to work or have increased productivity at work earlier, particularly in those in more manual
professions. A decision was therefore taken to include questions relating to employment and presenteeism (reduced productivity in the workplace as a result of health problems).
A decision was taken not to ask patients or parents to self-report income, as there was concern that they may be reluctant to provide such personal information; we did, however, obtain data on occupation.
The wide range of ages necessitated the development of two versions of the resource use questionnaire, one for adults (defined in this context as aged≥16 years to coincide with the adoption of the EQ-5D-5L), and one for parent completion in the case of children (aged≤15 years).
The number of visits to the burns clinic was specified in the trial protocol, as was the management by the site of massage, moisturisation and the application of silicone gel. The location of the pressure garment and the date on which pressure garments were fitted was recorded by staff at the treatment centres via the case report form (CRF). It was planned that cost data relating to different types of pressure garment would be obtained from a commercial price list used by the majority of the sites.
Willingness to pay
The inclusion of the WTP questionnaire was intended both to (1) value the impact of the treatment using a single, monetary metric, across all age ranges, given that–ultimately–two different sets of utility values would be elicited (from EQ-5D-5L and from CHU-9D–directly and indirectly) and (2) allow patients/parents to value outcomes that they have reason to consider relevant and important. This was especially important as the HRQoL instruments could only crudely incorporate outcomes, such as the patient’s own perceptions of changes in scar appearance, or aspects of treatment such as itch; information and compassionate care provided by staff; and inconvenience. The value of such aspects of treatment (Mooney54also suggests that these may include dignity and autonomy) can be thought of in terms of‘process utility’.54This is not a limitation of the measures as such, but instead stems from a normative stance within cost–utility analysis that the sole objective is to maximise health outcomes.
Two versions of the WTP questionnaire were developed, for PGT and no-PGT patients (seeAppendices 5
and6), both to be administered at the 6-month follow-up. Both groups were asked to value the impact of the treatment that they had actually received (an ex post perspective), although the PGT patients were also provided with (or rather were reminded of, given that they had received an information leaflet at the time of recruitment) a short description of the difference between the two treatment arms, and asked the additional question:‘If you could pay a smaller amount per month to receive the same treatment but without the tight fitting Lycra garment, would you choose to do so?’, with the follow-up question, if yes, of‘I would pay £__ per month for this treatment’.
The 6-month follow-up was chosen to give sufficient time for patients or parents to experience treatment because not all patients were followed up at 12 months. Owing to resource constraints, it was planned that the questionnaire would be given out at the centre (by the usual centre staff) with the‘standard’questionnaires.
Summary
l The wide age range included in the sample required that three different health economics instruments be chosen to capture health outcomes: EQ-5D-5L (for patients aged≥16 years); CHU-9D (for ages 7–16 years, and with further differentiation within this age range relating to patient vs. proxy completion); and PedsQL (for ages 2–4 years, with solely proxy completion).
l A WTP questionnaire was introduced to enable patients and parents to value outcomes broader than ‘just’health. Two versions of the WTP questionnaire were developed (one for each treatment arm) so that patients could place a value on the care they had actually received.
l A NHS and societal perspective was adopted to capture and record cost data. Information that was not routinely captured on the CRF would be elicited directly from the patient or parent. Costing for