Abstract
Atypical haemolytic uremic syndrome (aHUS) is a rare disorder characterised by complement-mediated thrombotic microangiopathy (TMA). Despite clinical guidelines, the diagnosis and treatment of aHUS in its early stages remains challenging. This study examined the annual trends in aHUS clinical practices in Japan and explored factors influencing early diagnosis and treatment. Using data from the 2011-2020 Diagnosis Procedure Combination database, 3096 cases with the HUS disease code were identified, of which 217 were confirmed as aHUS and treated with eculizumab or plasma exchange. Early initiation, defined as starting eculizumab or plasma exchange within 7 days of admission, was the focus of the study. Our study revealed no significant changes over time in the number of aHUS diagnoses, cases treated with eculizumab, or early initiation cases. Early initiation cases underwent haemodialysis earlier and had ADAMTS13 activity measured earlier, shorter hospital stays, and lower hospitalisation costs than late initiation cases. In conclusion, we found no increase in the number of newly diagnosed aHUS cases or early treatment initiation over time. Early recognition of TMA and differentiation of the causative disease are crucial for identifying potential aHUS cases, which may lead to better patient prognoses.