OBJECTIVES: Inherited retinal dystrophies (IRD) are a heterogeneous group of rare genetic diseases that cause progressive vision loss leading to near total blindness due to gene mutations, including the RPE65 gene. This study objective was to estimate long-term costs and impact on quality of life in patients with RPE65‑mediated IRD in Portugal.

METHODS: The progression of patients with RPE65-IRD was estimated using a Markov model with six health states defined according to visual acuity and visual field scores: moderate visual impairment (VI); severe VI; profound VI; counting fingers; hand motion, light perception to no light perception; and death.

Baseline characteristics and short-term transition probabilities were derived from trial 301/302, in which voretigene neparvovec was compared to best supportive care. Long-term progression was based on a natural history study.

Portuguese-specific disease management resource use was based on a panel of clinical experts and on Portuguese diagnosis-related group microdata. The main sources for unit costs were national legislation and official drug cost databases. The analysis was conducted from the societal perspective, assuming a lifetime horizon and a 5% discount rate.

EQ-5D-5L utility weights, valued according to Portuguese tariffs, were based on a vignette study in which a panel of clinical experts was interviewed.

RESULTS: Patients with RPE65-IRD have a discounted life expectancy of 19.4 years that are reduced to 9.7 when considering quality-adjusted life years (QALY). During lifetime, direct costs amount to 75,714€ and productivity costs to 78,630€. If it would be possible to maintain individuals in the moderate VI health state, patients would benefit from 16.4 QALY, their lifetime direct costs would be reduced to 20,049€, and productivity costs completely avoided.

CONCLUSIONS: RPE65-IRD translates into significant humanistic and economic burden. Treatment could potentially increase quality-adjusted life expectancy by 6.7 QALY and decrease lifetime costs by 134,296€ highlighting an unmet clinical need.