Blindness is one of the most serious microvascular complications of diabetes. The most common cause is diabetic macular oedema (DME). Current treatment with lasers is often unsuccessful.
The new injectable drug ranibizumab, which works by selectively inhibiting vascular enothelial growth factor A, has been seen in the RESTORE trial to improve visual acuity and quality of life, when used alone or in combination with laser treatment.
This review set out to assess whether these benefits are worth the costs in a UK context.
In people with diabetic macular oedema, is ranibizumab cost-effective compared with laser treatment alone?
Visual impairment was measured using Best Corrected Visual Acuity (BCVA) score. The analysis included the use of ranibizumab in combination with laser therapy as well as on its own.
The analysis took its effectiveness data from the RESTORE study and extended them to a 15-year time period.
The proportion with severe visual impairment in the treated eye was predicted to be 12% and 13% in the ranibizumab monotherapy and combination therapy groups respectively, versus 19% in the laser monotherapy group.Quality-adjusted life-years (QALYs) were estimated from outcomes data from the same study.
Ranibizumab monotherapy was associated with an incremental gain of 0.17 QALY and cost of £4 191, corresponding to an ICER of £24 028 per QALY gained relative to laser monotherapy
Cost data were derived from reference data for the likely outcomes and from the manufacturer’s cost data.
The researchers concluded:
Ranibizumab monotherapy was associated with an incremental gain of 0.17 QALY and cost of £4 191, corresponding to an ICER of £24 028 per QALY gained relative to laser monotherapy.
- Does the RESTORE study provide sufficiently compelling evidence to justify the assumptions of effectiveness and quality of life?
- Are the costs and quality of life estimates allocated to the end states realistic?
- Do they include the relevant perspectives?
- It is notable that combination therapy was considered to be less effective than monotherapy. This may be because participants who received combination therapy
- The model does not report confidence intervals. It seems that, given the broad range of assumptions and diverse sources of reference data, there remains considerable uncertainty around the findings.
- The researchers note that their model’s sensitivity analysis demonstrated that the finding was robust to most important changes in input data. It was most affected by increasing the number of injections required to achieve benefit, and by increasing the time horizon of the analysis. They consider their assumptions to be conservative in these respects. Future data from the RESTORE will provide more data.
- The model did not include treatment in both eyes. This case was cited by NICE as part of its rationale for not approving ranibizumab in 2011.
The full text of this analysis is available from PubMed Central.
Mitchell P, Annemans L, Gallagher M, Hasan R, Thomas S, Gairy K, Knudsen M, Onwordi H. Cost-effectiveness of ranibizumab in treatment of diabetic macular oedema (DME) causing visual impairment: evidence from the RESTORE trial. Br J Ophthalmol. 2012 May;96(5):688-93.
Mitchell P, Bandello F, et al. The RESTORE study: ranibizumab monotherapy or combined with laser versus laser monotherapy for diabetic macular edema. Ophthalmology. 2011 Apr;118(4):615-25.