Verteporfin photodynamic therapy for neovascular age-related ...

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72 Discussion of resultsA further concern that has been previously expressed is that the utilities for the HUI3 havebeen derived from a power transformation of values from a visual analogue scale, 72 ratherthan by direct valuation with choice-based methods such as the standard gamble (used for theSF-6D) or the time trade-off (used for the EQ-5D). Our approach of using the SF-6D followsthe recommendations of policy-makers such as NICE. 15 Therefore, it is not surprising that ourfindings are consistent with previous studies that have used the EQ-5D. 64In terms of an internationally recognised measure of HRQoL appropriately based on societalpreferences, the gradient of the decrease in HRQoL with deteriorating visual function is small.The estimated gain in HRQoL (utility) from VPDT is about 0.02 (in terms of BCVA, a differenceof about 11 letters after 2 years, assuming that only the best-seeing eye is being treated), andfrom ranibizumab is about 0.04 (a difference of about 21 letters after 2 years, 73,74 under the sameassumption). Gains in utility (over varying time horizons) for other common interventions forchronic conditions (Table 23) show that the utility gain associated with VPDT is relatively smallcompared with other competing interventions. 75,76 These utilities measured over the appropriatetime horizon, and combined with relative effects on life years gained, translate into QALYs andinform health policy decisions.Cost of illness and resource utilisationThe VPDT cohort study, unlike most other studies used to estimate cost-effectiveness, collecteddata concurrently on both resource utilisation and HRQoL. Thus, it was able to report on thecost-effectiveness of VPDT versus BSC under the assumption that BSC involved scheduled visitsto the ophthalmology clinic to monitor patients’ vision and no other treatment.The main empirical finding from the CEA is that the costs of providing VPDT for patientsincluded in the UK VPDT cohort study were relatively high compared with the projected QALYTABLE 23 Utility gains of VPDT compared with other common interventionsIntervention a Utility gain b Duration of follow-up c Measure used dCataract surgery 0.03 3 months EQ-5DGroin hernia repair 0.06 3 months EQ-5DTotal hip replacement 0.42 6 months EQ-5DVaricose vein surgery 0.10 3 months EQ-5DTotal knee replacement 0.31 6 months EQ-5DCoronary artery bypass grafting 0.21 6 years EQ-5DVPDT e Year 1: 0.009; year 2: 0.012; total: 0.021 2 years SF-6Da The utility gains shown were selected as comparators because the data were collected when the interventions were provided in usualhealth-care clinical settings. Utilities for five surgical interventions (cataract, hernia, varicose veins, knee replacement surgery and total hipreplacement) were obtained from the Patient Reported Outcome Measures (PROMs II) project. 75 Utilities before and after coronary arterybypass grafting were elicited from patients rated clinically appropriate for both bypass surgery and percutaneous management in theAppropriateness of Coronary Revascularisation (ACRE) study. 76b All of the utilities were measured before and after the intervention.c The utility gains are reported for different durations of follow-up after an intervention, so they are not directly comparable. In general, onewould expect the utility gain to be larger with a longer duration of follow-up. Note that the 2-year utility gain from VPDT is still lower than theutility gains achieved over a shorter durations for the interventions studied in the PROMs II project.d The PROMs II and ACRE studies measured utility gains using the EQ-5D, 75,76 whereas the VPDT cohort study measured utility using the SF-6D.The EQ-5D and SF-6D have been shown to differ when used to report extreme health states; 70 the EQ-5D appears unable to discriminatehealth states close to full health (ceiling effect), whereas the SF-6D seems unable to discriminate health states close to zero (floor effect).However, on average the two instruments generate utilities that are very similar each other, with a mean difference of only 0.05, 70 so thedifferences shown in the table cannot be explained by the use of different utility measures.e The estimate for photodynamic therapy assumes that the better-seeing eye is being treated (see text).
DOI: 10.3310/hta16060Health Technology Assessment 2012; Vol. 16: No. 673gain. The incremental cost per QALY was £170,000 over 2 years for the base case. Even if thegain from the intervention was extrapolated over 5 years, the incremental cost per QALY wasstill approximately £100,000, five times higher than the threshold that NICE uses to identifyinterventions that are ‘relatively cost-effective’. 15 The cost-effectiveness ratios reported in previousCEA of VPDT for nAMD have ranged from US$30,000 to US$250,000 (£20,000 to £166,667assuming an exchange rate of US$1.5 to the UK pound). 26,28 Unlike previous CEA of VPDTfor patients with predominantly classic CNV secondary to nAMD, we were able to include allappropriate costs and account for HRQoL associated with vision loss. This resulted in improvedpatient-centred estimates that showed that VPDT is unlikely to be cost-effective.There are three other features of our CEA that are relevant to future CEA of interventions fornAMD. Firstly, the study used data on the use of a treatment in routine practice rather than datacollected in accordance with a trial protocol. Despite the much lower treatment frequency, weobserved similar visual outcomes to those observed in the TAP trials. In the case of our CEA,it was more appropriate to use the lower treatment frequency observed in the VPDT cohortstudy, and previous CEAs that used treatment frequencies from the TAP trials overstated theincremental costs of the VPDT intervention compared with BSC. 19,26,77 The lesson for future CEAis that treatment intensities observed in licensing trials may overestimate the treatment intensityused in routine practice and, hence, overestimate the costs of treatment in the usual care setting.Second, previous CEAs either excluded costs associated with declining vision or estimatedthese costs based on expert opinion. 19,26,28,77–79 By contrast, by collecting patient-level data onHSS resource use and BCVA, our CEA was able to incorporate the cost of declining vision. Ourdata showed that the HSS costs for patients with nAMD were low (e.g. a mean of £320 for BSCgroup in year 1), and hence the reduction in these costs after VPDT was relatively small (£151over 2 years). The costs were lower than those reported by a recent observational study assessingthe economic burden of nAMD by self-reported use from 400 patients across five differentcountries 23 and from studies of Medicare costs based on claims data. 80,81 However, these studieswere based on aggregated costing approaches, which tend to overstate costs. The morbiditycosts observed in the VPDT cohort study relied entirely on patient recall and therefore mayhave under-represented the true cost, and also they may reflect the relatively poor availability oflow-vision services in the UK; previous studies have found a similarly low use of vision-relatedservices in the UK. 82,83 However, this low use of vision services has been reported in othercountries that have used patient-level data, which suggests that the current findings may be morewidely applicable. 24 The lesson for future CEA is that the source and robustness of data describingcosts associated with declining vision need to appraised with care.The third feature of our CEA that is relevant to future CEA concerns the importance of usingHRQoL measures based on preference weights from the general population rather than patientswith nAMD.A final issue for future CEAs which emerged from the VPDT study but which was notincorporated into our CEA was the relationship between BCVA and HRQoL. The regressionmodels which investigated this relationship found that the rate of change in HRQoL with varyingBCVA was not influenced by whether the better- or the worse-seeing eye was being treated.However, a key assumption in this and other CEA is that it is always the better-seeing eye thatis being treated, as the HRQoL gain is ‘credited’ for all treated eyes. Unless policy-makers rulethat worse-seeing or ‘first’ eyes should not be treated (an option considered but rejected byNICE during its deliberations prior to issuing its technology appraisal 6 ), the worse-seeing eyewill be treated in a proportion of patients (48% in the VPDT cohort study). Therefore, the CEAreported here (and other CEAs) has overstated the QALY gain and the cost-effectiveness of© Queen’s Printer and Controller of HMSO 2012. This work was produced by Reeves et al. under the terms of a commissioning contract issued by theSecretary of State for Health.
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xExecutive summaryretreat on criter
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2 Introductionon-going or new clini
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4 Introductionof VPDT in routine cl
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20 Key changes to the protocolThese
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Page 98 and 99: 84 References16. Stelmack J. Qualit
Page 100 and 101: 86 References49. Guymer RH, Chiu AW
Page 102 and 103: 88 References83. Margrain TH. Minim
Page 104 and 105: 90 Appendix 1THE VERTEPORFIN PHOTOD
Page 106 and 107: 92 Appendix 11. Overview of Manual
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Page 110 and 111: 96 Appendix 1more patients in the v
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Page 124 and 125: 110 Appendix 1The Verteporfin Photo
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122 Appendix 112. Data issues12.1 D
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124 Appendix 113. Organisation13.1
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126 Appendix 114. References[1] Ref
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128 Appendix 1Barnes RM, Gee L, Tay
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130 Appendix 1Appendix 1: Classifyi
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132 Appendix 1Liverpool re-treatmen
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134 Appendix 1Service StructurePlea
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136 Appendix 1Has your photographer
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138 Appendix 1There are many differ
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140 Appendix 1testing on vision tes
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142 Appendix 1something to do with
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144 Appendix 1College of Ophthalmol
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146 Appendix 1Appendix 5:Protocol f
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148 Appendix 16.2 Subjective Refrac
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150 Appendix 1• The patient shoul
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152 Appendix 1Appendix 6:Protocol f
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154 Appendix 18. It is customary to
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158 Appendix 1
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166 Appendix 1Appendix 9:Site imple
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170 Appendix 1Dos and Don’tsDosDo
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172 Appendix 1Resource use question
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174 Appendix 1Appendix 11: Recommen
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176 Appendix 1ADVERSE REACTION AND
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178 Appendix 1acute Trust; note tha
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180 Appendix 1Ophthalmologistrespon
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192 Appendix 3manufacturer’s pers
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FeedbackThe HTA programme and the a
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