Modeling Manifest Huntington's Disease Prevalence Using Diagnosed Incidence and Survival Time

Introduction Understanding the epidemiology of Huntington's disease (HD) is key to assessing disease burden and the healthcare resources required to meet patients' needs. We aimed to develop and validate a model to estimate the diagnosed prevalence of manifest HD by the Shoulson-Fahn stage. Methods A literature review identified epidemiological data from Brazil, Canada, France, Germany, Italy, Spain, the UK, and the USA. Data on staging distribution at diagnosis, progression, and mortality were derived from Enroll-HD. Newly diagnosed patients with manifest HD were simulated by applying annual diagnosed incidence rates to the total population in each country, each year from 1950 onwards. The number of diagnosed prevalent patients from the previous year who remained in each stage was estimated in line with the probability of death or progression. Diagnosed prevalence in 2020 was estimated as the sum of simulated patients, from all the incident cohorts, still alive. Results The model estimates that in 2020, there were 66,787 individuals diagnosed with HD in the 8 included countries, of whom 62-63% were in Shoulson-Fahn stages 1 and 2 (with less severely limited functional capacity than those in stages 3-5). Diagnosed prevalence is estimated to be 8.2-9.0 per 100,000 in the USA, Canada, and the 5 included European countries and 3.5 per 100,000 in Brazil. Conclusion The modeled estimates generally accord with the previously published data. This analysis contributes to better understanding of the epidemiology of HD and highlights areas of uncertainty.