CONTEXT: The hypersomnolence disorder diagnostic criteria of the DSM-5-TR rely on the report of a 'hypersomnolence' syndrome, without defining the term or proposing any measuring tool to assess this. Among the vast diversity of tools to measure hypersomnolence, the Hypersomnia Severity Index (HSI) has been specifically designed to account for the multidimensionality of hypersomnolence. Showing good psychometric validity in two previous validation studies, the HSI has never been validated against the gold-standard Multiple Sleep Latency Test (MSLT). OBJECTIVE: This preliminary study aims to validate the French version of the HSI and to provide a first exploration of the link between HSI and the MSLT in a group of French subjects clinically diagnosed with hypersomnolence disorders. In addition, we propose an original visualization of the dimensions of the HSI. METHOD: This study is a secondary analysis of a cohort of 34 patients diagnosed with hypersomnolence disorders without comorbidity. They underwent a MSLT and filled out the French version HSI as well as classical sleep medicine questionnaires. The HSI has undergone a rigorous translation and psychometric validation, which we compare with two previous psychometric validation studies. RESULTS: We obtained the same level of psychometric validity as previous studies, validating our French version on a population of patients with hypersomnolence disorder. However, we did not find any correlation between the HSI and the MSLT. Nevertheless, the dimensional approach offered by the HSI combined with our data visualization provide a valuable tool for sleep medicine clinical practice and research.
Martin et al. (Wed,) studied this question.