Unclassified Versus Well-defined Platelet Function Disorders: A Multicenter Comparison of Bleeding Patterns and Treatment

INTRODUCTION: Platelet function disorders (PFDs) are caused by abnormalities in platelet receptors, granules, and signaling pathways. While severe conditions like Glanzmann Thrombasthenia (GT) and Bernard-Soulier Syndrome (BSS) have well-characterized bleeding phenotypes, other PFDs remain less defined. This study aimed to describe the bleeding phenotype in different PFDs at the time of diagnosis and during longitudinal follow-up and compare bleeding symptoms and health care utilization for bleed management. METHODS: This retrospective multicenter study analyzed data from 129 patients diagnosed with PFDs at 3 Hemophilia Treatment Centers in the United States from 2015 to 2020. Data included demographics, bleeding symptoms, and treatment utilization. Statistical comparisons of bleeding symptoms, frequency, and treatment across PFDs were performed using the χ 2 or the Fisher exact tests. RESULTS: Among 129 patients, 8 had GT, 2 had BSS, 40 had platelet storage pool disorder, 7 had platelet secretion defect, and 72 had PFD not otherwise specified (NOS). Epistaxis was the most common symptom at diagnosis, except in platelet secretion defects, where soft tissue bleeding predominated. Heavy menstrual bleeding affected 31.7% of females. Over a 5-year period, epistaxis remained frequent in GT and PFD NOS. GT had the highest treatment burden, with 86.2% of bleeds requiring treatment. Hospitalizations were significantly greater in GT and platelet secretion defects. CONCLUSION: Individuals with PFD NOS and platelet secretion defects can experience serious bleeding. Life-threatening bleeds occur in PFDs beyond GT and BSS, necessitating thorough evaluation, close follow-up, and careful perioperative planning. Unclassified platelet disorders require further evaluation along with genetic testing to prevent excessive blood loss.