Background The REGISTRY study was designed to obtain natural history data on a wide spectrum of HD patients in Europe over the course of 15 years. Several scales were administered to characterise and evaluate HD patients’ progression, which included the Unified Huntington’s Disease Rating Scale (UHDRS).

Aims The aim of this study was to evaluate the validity of translations of UHDRS to German, French, Italian, Dutch, Polish, Portuguese and Spanish as applied in the REGISTRY study.

Methods/techniques This study was submitted to European Huntington’s Disease Network Scientific Bio-ethics Assessment Committee for authorisation and access to the REGISTRY data. Data was provided with baseline and follow up evaluations, by country and site. The analysis was performed for translated versions of the UHDRS if a minimum of 100 cases were observed per language and limited to HD gene expansion carriers with manifest disease. Statistical analysis included Cronbach’s alpha and Confirmatory Factorial Analysis (CFA) trough SPSS and R software.

Results/outcome A total of 6.009 manifest HD patients were analysed from 8 different languages (English was used as a control language), 53% female with a mean age of 48.2 years (SD 13.8), age-at-onset of 45 years (SD 12.3) and a CAG of 44.3 (SD 4.9). Cronbach’s alpha results showed a high internal consistency in each of the four components of the UHDRS for all translated languages. Regardless the language assessed, CFA analysis demonstrated that motor items of dystonia, chorea and arms rigidity, and most of the behavioural items are not well explained by their respective latent component, with loadings below 0.7.

Conclusions Results demonstrate that the translation process used in the REGISTRY did not affect UHDRS structure and basic clinemetrics indices across the different languages. However, this analysis revealed structural issues concerning UHDRS and its latent dimensions which require further evaluation.