Epidemiology, Management, and Outcome of Atypical Hemolytic Uremic Syndrome in an Omani Cohort.

Objectives: Atypical hemolytic uremic syndrome (aHUS) is a rare, life-threatening disease of chronic uncontrolled complement pathway activation that leads to thrombotic-microangiopathy, along with severe organ damage, including end-stage kidney disease. This study aimed to evaluate the epidemiology, management, and outcome of aHUS in an Omani population. Methods: This retrospective descriptive cohort study assessed all cases of aHUS diagnosed and followed up at two tertiary care centers in Oman from January 2008 to December 2019, based on clinical features, complement pathway assays, histopathological, and genetic testing. Results: The study accrued 19 patients who fulfilled the inclusion criteria, of whom 11 (57.9%) were male. The participants' median age was 25.0 years (range = 0.1-69.0). Most (15; 78.9%) patients presented in the acute phase of the disease. The triad of hemolytic anemia, acute kidney injury, and thrombocytopenia was present in all patients. A trigger factor (e.g., infection) was identified in 68.4% of cases. Of the 14 (73.7%) patients who underwent kidney biopsy, 10 (71.4%) were found to have aHUS in native kidneys and three in grafted kidneys. Of the 11 (57.9%) patients who underwent genetic analysis, five (45.5%) were found to have a known pathogenic variant in their aHUS susceptibility genes. Plasma exchange followed by eculizumab was the treatment method in 11 (57.9%) cases. Complete renal recovery was achieved in seven (36.8%) patients, while four (21.1%) passed away during the study period. Conclusions: The wide spectrum and multiple expressions of aHUS make it a challenge to diagnose and consequently may delay the commencement of the targeted treatment. Eculizumab is considered the first-line therapy and should be commenced as early as possible.