OBJECTIVES: Previous studies showed that the willingness-to-pay of public decision makers is higher for orphan drugs. However, price determinants among orphan drugs in France are not well understood. We investigated which characteristics of orphan drugs are associated with public prices.

METHODS: Data on orphan drugs appraised by the Haute Autorité de Santé since 2018 were obtained from the NaviHTA database. Drug price was defined as the annualized drug acquisition costs allowing for wastage, were computed based on public unit prices. Exploratory data analysis was performed to identify associations between prices and characteristics such as oncological indication, paediatric population, availability of treatment alternatives, level of unmet medical needs and clinical study methods. Pairwise associations between the price and its potential determinants were tested using Kolmogorov-Smirnov (KS) tests. A generalised linear model with logarithmic link function was fitted to estimate marginal effects of different variables.

RESULTS: After excluding 6 outliers, 73 drug evaluations were included. KS tests showed a significant association of the price distribution with presence of an active treatment alternative (including off-label) (p-value = 0.048), paediatric population (p-value = 0.047), randomised study design (p-value < 0.001) and unmet medical needs (p-value = 0.01). According to the regression model, a cancer indication was associated with a 78% higher price, paediatric indication with a 95% higher price and availability of a treatment alternative with a 133% higher price. No significant impact of health outcome improvements (including existing of a gain in overall survival) or clinical study methods was found.

CONCLUSIONS: The prices of orphan drugs appear to be mostly driven by cancer indication, paediatric population and availability of an active treatment alternative.