Characterising Glanzmann Thrombasthenia in the United States: Real‐World Data From the EPIC Cosmos Dataset

Background Glanzmann Thrombasthenia (GT) is a rare autosomal recessive bleeding disorder characterised by defective platelet aggregation due to abnormalities in the glycoprotein IIb/IIIa complex. With a lack of large real‐world database studies, our study aimed to characterise the demographic, clinical and treatment profiles of GT patients using a large, national database. Methods A retrospective cohort study was conducted using the EPIC Cosmos database from 1 January 2013 to 31 December 2024. Patients with at least one encounter coded with the SNOMED code for GT (32942005) were included. The primary outcome was the prevalence of GT, calculated using the total database population as the denominator. Secondary outcomes included bleeding manifestations, comorbidities, transfusion utilisation, medication use, sex‐based differences and mortality, with statistical comparisons performed using Chi‐squared tests. Results A total of 1059 GT patients were identified, 58.5% female. The estimated prevalence of GT was 1 in 352,435, higher than prior US estimates. The most frequent bleeding manifestations were abnormal uterine bleeding (29.7% of females aged 11–45), epistaxis (22.6%) and hematuria (16.1%). Anaemia was the most common comorbidity (35.6%), with iron deficiency anaemia present in 31.0%. Transfusion dependency was frequent, with 16.4% of patients requiring blood or component transfusions. No significant sex‐based differences were observed. Mortality increased with age, with an overall annualised rate of 1222 per 100,000 GT patients, exceeding that of the general US population. Conclusion GT is more prevalent in the United States than previously recognised and is associated with substantial clinical burden from recurrent bleeding, anaemia and transfusion dependency.