OBJECTIVES: The NICE considers since 2011 that a lower discount rate (1.5% instead of 3.5%) can be used for health outcomes in cases of interventions that provide substantial effects in restoring health, sustained on a very long period. The impact of this amendment could be significant for gene therapies, which would be associated with high initial costs and substantial long-term health benefits. As several gene therapies are getting close to appraisal by HTA agencies, our objective was to assess the impact of differentiating discount rates on the incremental cost-effectiveness ratio.

METHODS: We developed a simple model for an infantile genetic disease, with fictitious data. We considered life expectancies from 3 to 20 years in the absence of treatment, and from 40 to 50 years for patients receiving a gene therapy. We assumed the constant utility of the health state of living patient equal to 0.8. The use of gene therapy was assumed not to have any impact on patients’ quality of life. Cost spread of gene therapy on 5, 10 or 20 years was also considered.

RESULTS: The use of the lower discount rate for health outcomes leads to lower ICERs for gene therapy compared to no treatment. The difference varies from 36% to 49% depending on the assumed life expectancy. At the assumed price of 300 k£, the gene therapy could be cost-effective intervention (at the threshold of 30 k£) even when considering the lowest incremental gain in life expectancy. When the highest incremental gain was considered, the gene therapy would be cost-effective for a price up to 800 k£ with a discount rate 1.5% vs. 500 k£ with a discount rate of 3.5%.

CONCLUSIONS: Considering a lower discount rate for health outcomes could have a high impact on the price of gene therapies, resulting in significant budgetary impact for health care payers.