Adverse factors associated with mortality among patients with immune-mediated thrombotic thrombocytopenic purpura in Taiwan: a single-institute cohort study

Abstract Background Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is caused by autoantibodies against ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) in conjunction with a severe deficiency in ADAMTS13 activity. It remains uncertain which subgroups are at a higher risk of death for patients with iTTP in Taiwan, where therapeutic plasma exchange (TPE) is the primary treatment. This study was conducted to investigate the clinical characteristics, treatment outcomes, and mortality risk factors in patients with iTTP in Taiwan. Methods Between 2012 and 2023, 22 patients with acute episodes of iTTP were enrolled. The clinical and laboratory findings at diagnosis, as well as the treatment strategy and outcomes, were retrospectively collected. The ADAMTS13 activities and anti-ADAMTS13 IgG levels were determined, using either a fluorescence resonance energy transfer (FRET)-based or an ELISA-based assay. Neutralizing autoantibodies against ADAMTS13 were determined by Bethesda methods. Results We enrolled 14 male and 8 female patients, with a median age of 61.5 years. All presented with microangiopathic hemolytic anemia and profound thrombocytopenia. Major and minor neurologic deficits were identified in 9 and 8 patients, respectively; serum creatinine levels exceeding 1.2 mg/mL were observed in seven cases. Elevated cardiac troponin-I levels were also found (in 11/11). At diagnosis, ADAMTS13 activities were less than 10%. Meanwhile, we confirmed the substantially high titers of autoantibodies against ADAMTS13. The regional incidence is estimated to be 0.73 per million person-years. The cardinal treatment strategy incorporated TPE and glucocorticoids. Only six patients received rituximab. Our approach led to a clinical response in 17 patients (77.2%), while the remaining five were refractory to treatment, which resulted in their death. Following the cessation of TPE, 13 patients sustained the response and obtained a clinical remission, eight of whom had an ADAMTS13 remission. However, four patients experienced exacerbations after initially responding to treatment. Additionally, three patients relapsed from their remissions. Mortality was associated with major neurologic impairment ( p = 0.005), elevated lactate dehydrogenase (LDH) exceeding 5-fold ( p = 0.039), and treatment-refractory cases ( p < 0.001). Conclusions The risk factors associated with mortality of iTTP patients in Taiwan are mainly consistent with those observed in larger cohorts. Trial registration CCH IRB 240804.