F08 Huntington’s disease burden of illness (HDBOI): study methodology, sample representativeness and fieldwork risk mitigation strategy during the COVID-19 pandemic

Background The prevalence of Huntington’s Disease (HD) has increased over time, augmenting the associated economic and humanistic burden. The HDBOI study aims to provide an up-to-date assessment of the burden of HD from a multinational perspective. Methods The HDBOI is a retrospective, cross-sectional dataset that captures demographic, clinical, and health resource utilization (HRU) of a cohort of HD patients, reported by treating physicians in multiple centres across the USA, Germany, Spain, Italy, France and the UK. Patients and caregivers reported information on health-related quality of life (HRQoL), non-medical and indirect costs associated with HD through optional questionnaires. The study has been governed by an Expert Review Group (ERG) that provided recommendations on the study design. Data was collected between September 2020 and May 2021. Patients and caregivers reported their HRQoL at the time of questionnaire completion, whereas physicians reported patient’s HRU for the 12-month period between March 2019 and March 2020, to avoid months with limited access to healthcare due to COVID-19. Other strategies were taken to mitigate the effect of COVID-19 on the fieldwork process: online questionnaires, extending the time in fieldwork, questions monitoring the effect of the pandemic on patients HRQoL and HRU. Results The HDBOI sample has 2,094 HD patients, of which 40% were early stage, 34% mid stage and 26% advanced stage, as assessed by the treating physician. Patient representation across countries was similar. For a subsample (N=718) the Shoulson and Fahn stages were determined by the treating physician: stage I (14.6%), II (24.4%), III (31.6%), IV (28.1%) and V (1.1%). The last figure was expected by the ERG, as advanced stage patients usually live in care homes and do not attend regular consultations. Conclusion The HDBOI study is a representative sample of the HD population across disease stages and studied countries, as confirmed by the ERG.