Calculating the prevalence of urea cycle disorders in the EU5 using an incidence-survival model

Objectives

Gene therapies for rare diseases have ignited industry-wide debates concerning patient access, pricing and efficacy. Urea cycle disorder (UCD), a genetic rare disease, is a target for enzyme replacement therapies, yet UCD epidemiology data are scarce. The objective of this study is to estimate the prevalence of UCD in the 0–17 year-old population in five major European markets (EU5) (France, Germany, Italy, Spain, UK).

Methods

We designed an incidence-survival model utilizing birth incidence, annual life-expectancy and country-specific newborn data. Birth incidence estimates for UCD were obtained from the Urea Cycle Disorders Consortium (UCDC). We conducted a literature review to determine the annual life expectancy of UCD. Finally, we reviewed available EU5 newborn census data to obtain the number of newborns in each country from 2001 to 2012. We extrapolated the trend from 2001-2012 to forecast the number of newborns through 2024. These data were entered into the incidence-survival model to calculate the prevalence of UCD from 2015-2024.

Results

We estimated a prevalence of 1.71 per 100,000 population in the 0–17 year age groups resulting in 1,027 and 1,033 UCD cases in the EU5 in 2015 and 2024, respectively. The prevalence was 1.89 per 100,000 in the 0-4 year-old age group, 1.63 per 100,000 in the 10-14 year-old age group, and 1.57 per 100,000 in 15-17 year-old age group.

Conclusions

To our knowledge, this study provides the first prevalence estimate of UCD in the EU5 markets. With 1,027 estimated cases in 2015, it is expected that UCD treatments will be expensive given the small size of the patient population. Further, these estimates can be used to approximate the total cost burden of UCD and the resulting cost-effectiveness of UCD treatments