AOSD: Young vs. Elderly Onset Save

Adult onset still's disease (AOSD) is an autoinflammatory condition characterized by fevers, arthritis, and rash. It is considered an orphan disease because of its low prevalence - it is reported anywhere between 16 to 40 per ten million. Traditionally, a bimodal distribution by age has been reported with peaks at the ages of 15 to 25 and between 36 to 46. 

In a prior study done by our group, we reported a significant number of older patients above the age of 65 with AOSD being hospitalized in a nationwide US study. 

One very interesting study at #EULAR2023 (POS0962) specifically tried to characterize patients with young onset and elderly onset Still's disease (these were defined as those who had symptoms after the age of 65 years). This Japanese study was a single center study where they reviewed 103 patients from 10 years retrospectively. 

One of the key takeaways from the study is that about 19% of the patients were elderly onset Still's disease and thus clinically very relevant, as traditionally it was thought that AOSD mostly presents in younger age groups. Also that in the recent years elderly onset disease diagnosis was much more than before 2000. It raises the question if there is more awareness about the disease and thus it is being  diagnosed or there are environmental or other triggers which are increasing the prevalence in this age group. This group was also much sicker -i.e. higher frequency of serositis, interstitial lung disease, median Pouchot Score, length of stay, incidence of hospitalization as well as incidence of infectious complications leading to hospitalization. The younger onset AOSD patients on the other hand had a higher incidence of a typical rash, sore throat and splenomegaly. 

As we understand more and more about autoinflammatory diseases, we need to disseminate this information not only in patient care but also in teaching. While there are talks about the nomenclature of sJIA and AOSD being in the same spectrum of disease, understanding nuances in clinical manifestations diagnosis and outcomes is important. Studies like this comparing differences in characteristics of younger onset and elderly onset AOSD will become more and more important as we move towards precision medicine in rare disease patients.