Cost-Effectiveness Analysis of Idursulfase for the Long-Term Treatment of Hunter Syndrome Using a Partitioned-Survival Model Approach in R

Objectives

Hunter syndrome is among the costliest life-long genetic conditions associated with a substantial burden-of-illness and a significant impact on the health systems, families, and society. We estimated the cost-effectiveness of long-term enzyme replacement therapy with idursulfase versus the standard of care from a societal perspective using a streamlined modeling strategy in R.

Methods

A de novo 4-state partitioned survival model was developed to compare lifetime cost and outcomes of 2 care models operationalized in R. The disease progression was based on independent survival modeling of relevant Kaplan-Meier data. The healthcare and out-of-pocket costs were drawn from the local setting. The quality of life was measured using the EQ5D5L and the time trade-off valuation of health-state vignettes that match the states in the model. Probabilistic and deterministic sensitivity analyses were conducted to test the uncertainty around the model results.

Results

The lifetime incremental quality-adjusted life years were 4.1 years (95% CI, 2.37-5.68). Incremental costs were estimated to be $9.5 million (95% CI, 9.0 million-10.0 million), which primarily consists of drug costs (99%). The incremental costs per quality-adjusted life year were estimated to be approximately $2.4 million (95% CI, 1.7 million-3.8 million). Sensitivity analyses showed that the key drivers of incremental cost-effectiveness ratio were quality of life in the preprogression state and differential discounting approach, besides the acquisition cost of enzyme replacement therapy of idursulfase.

Conclusions

The incremental cost-effectiveness ratios were beyond any conventionally used cost-effectiveness threshold in all cases. At the current price, there is a significant discrepancy between the therapy’s funding decision and the cost-effectiveness assessment as a basis for guiding healthcare prioritization in Malaysia.