| Analysis, parameter(s) to be changed | Default parameter value | Value tested | Rationale |
|---|---|---|---|
| 1. FEV1% strata utility values | Novartis analyses of Bradley 2010 | Solem 2014: FEV1%>70, 0.949 FEV1% 40–70, 0.918 FEV1% < 40%, 0.881 | Solem 2014 is a larger and more recent RCT that used data from a 48-week, Phase 3, multicentre study (STRIVE) to evaluate the relationship between EQ5D measures and FEV1% in 161 participants with CF. Solem 2014 was also used to inform a recent NICE TA398 |
| 2. Tinnitus excluded | 3.1% | 0% | TRAEs have not been included in previous economic evaluations in this area |
| 3. Exacerbation cost | £6,827 | £1,220 | The cost used to inform the models for NICE TA276 based on asthma complications was a lot cheaper than the cost reported by Thornton 2005 |
| 4. Number of exacerbations | 1 | 2 | The NMA outcome (at least 1 exacerbation) does not specify the number of exacerbations experienced |
| 5. FEV1% MD, tobramycin dry powder versus placebo | 4.4 (Galeva 2013) | 13.3 (Konstan 2011) | The studies were too heterogeneous to perform NMA, but both populations could be applicable to a UK population today |
| 6. FEV1% MD, nebulised tobramycin versus placebo | 6.7 (Chucalin 2007) | 13.58 (Lenoir 2007) | The studies were too heterogeneous to perform NMA, but both populations could be applicable to a UK population today |
| 7. Within-trial (time horizon reduced) | Lifetime (60 years) | 2 cycles | There is uncertainty surrounding the extrapolation of the 24-week efficacy data to a lifetime horizon |
| 8. Hodson 2002 clinical effectiveness | Benefits for nebulised tobramycin and nebulised colistimethate sodium over 4-weeks are maintained over the time horizon applied in the model | The month-off nebulised tobramycin follows the treatment effect for placebo, whilst the benefit from nebulised colistimethate sodium is maintained | The consequence of assuming a ‘month-on, month-off’ regimen is that the modelled treatment benefits reflect those associated with the continued use of nebulised tobramycin at only half of the cost of generating those benefits. Unless nebulised tobramycin is priced at parity with the cost of nebulised colistimethate sodium, or a month-off cycle is applied where the benefits from nebulised tobramycin reflect placebo, a substantial bias in favour of tobramycin may exist. |
| 9. Hodson 2002 clinical effectiveness | The cost of nebulised tobramycin is priced continuously | ||
| 10. Nebulised colistimethate sodium drug cost | Colomycin® | Promixin® | The best price available to the NHS is used to inform the base case (NICE 2013 Guides to the methods of technology appraisal), but other more expensive brands and preparations are available |
| 11. Nebulised tobramycin drug cost | Tobi®/Tymbrineb® | Bramitob® | |
| 12. Nebulised colistimethate sodium dose | 2MU once daily | 2MU bd | The dose received by adults in clinical practice today is up to double that used in the studies, if dose is not linked to effectiveness, the base case will underestimate the cost of treatment |
| 13. Probabilities obtained from OR in WinBugs | Calculated externally | Calculated internally | Probabilities can be calculated from ORs directly from WinBUGS, or outside of WinBUGS. This scenario is to test the consistency of the modelling software rather than any specific assumption |
| 14. PAS prices | List price | Discounts | The DoH agrees discounts with the manufacturer to increase accessibility, these discounts are confidential but can be used to reassess cost-effectiveness for the NHS |
bd, twice daily, CF, cystic fibrosis; DoH, Department of Health; FEV, forced expiratory volume; OR, odds ratio; MD, mean difference; MU, million units; NMA, network meta-analysis; PAS, patient access scheme; TA, Technology Appraisal
From: Appendix K, Health Economics
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