Clinical Manifestations, Treatment Characteristics, and Clinical Outcomes in Patients with Immune Thrombotic Thrombocytopenic Purpura (iTTP) in a Real-World Setting: An Interim Analysis of the Turkish iTTP Registry

Objective: This study aimed to investigate the clinical manifestations, treatment patterns, and clinical outcomes of patients with immune thrombotic thrombocytopenic purpura (iTTP) across Türkiye via an interim analysis of the Turkish iTTP Registry. Materials and Methods: A total of 215 patients with iTTP (median age at diagnosis: 41 years; 58.6% female) diagnosed between 2001 and 2023 were retrospectively analyzed in the interim analysis of a prospective non-interventional observational multicenter iTTP registry study (ClinicalTrials.gov Identifier: NCT05950750) conducted at 19 tertiary hematology centers. Data on patient demographics, disease characteristics at initial admission, treatment characteristics and responses, exacerbations/relapses, and survival outcome were obtained from electronic case report forms. Results: Infection (15.0%), new drug initiation (9.7%), and pregnancy/postpartum period (6.3%) within 3 weeks before diagnosis were the most prevalent potential triggers. Patients presented most commonly with systemic/constitutional (fatigue: 68.8%; fever: 18.1%) and neurological (headache: 40.0%; vertigo: 32.1%) symptoms, followed by hemorrhagic, gastrointestinal, renal, and cardiovascular manifestations. Based on PLASMIC risk scoring, 77.8% of patients were initially at high risk for TTP. The initial treatment was begun within the first 48 hours of hospital admission for 64.1% of patients (36.2% on the day of admission). Treatment was mainly based on therapeutic plasma exchange (92.1%) and steroids (63.7%), while rituximab was used in 15.8% of patients. The clinical response rate was 79.9% and clinical remission was achieved by 68.2% of patients. Regarding a thrombospondin type 1 motif member (ADAMTS13) 13 levels, partial and complete responses were achieved by 17.7% and 14.6%, respectively. During a median of 30 months (range: 0.1-262.4 months) of follow-up, 35 patients experienced exacerbations/relapses. Mortality occurred in 11 (5.5%) patients and was found to be disease-related in 6 cases (3.0%). Conclusion: This interim analysis of the nationwide Turkish iTTP Registry study provides valuable data on real-world clinical practices in the diagnosis and management of iTTP at different hematology clinics across the country.