Design of the prospective randomized study for the treatment of patients with thrombotic microangiopathy. PRODROMI Study Group.

In thrombotic microangiopathies hemolytic uremic syndrome and thrombocytopenic purpura, plasma exchange (PE) therapy using fresh frozen plasma is standard. In almost 20% of the patients, however, this approach is ineffective. This prospective, randomized study for the treatment of patients with thrombotic microangiopathies (PRODROMI) compares PE with fresh frozen plasma (A) and cryosupernatant (B). The participating centers were the University Clinics of Freiburg, Hamburg, Düsseldorf, Essen, Göttingen, Mannheim, Ulm, Jena, Tübingen, Würzburg, Kreiskrankenhaus Offenburg, Städt Klinikum Karlsruhe, and Horst-Schmidt Kliniken in Wiesbaden, Germany. Patients (18 to 80 years) were diagnosed by the individual centers based on clinical and laboratory findings (thrombocyte/fragmentocyte count, hemoglobin, serum creatinine, haptoglobin and lactate dehydrogenase levels; negative Coombs-test is obligatory). HIV infection, bone marrow, or solid organ transplantation were exclusion criteria. After written consent, patients were randomized in the A or B group. All patients received 1.5 mg/kg methylprednisolone as a basic therapy. The first PE always was performed with fresh frozen plasma (50 ml/kg). A minimum of 5 and a maximum of 10 PEs were required. Thrombocyte count above 150,000/microl was considered to be a successful therapy. Treatment failure was defined as not responding to 10 PE with a thrombocyte count above 150,000/microl or a fall below this value within 30 days after stopping PE. Patients with clinical and laboratory signs of thrombotic microangiopathy occurring later than 30 days after having stopped PE were considered to have a relapse. Primary endpoints were survival, intensity of required PE sessions (duration, volume, and number), and relapse rate. Follow-up of clinical outcome was 2 years; von Willebrand Factor (vWF), vWF-cleaving-protease activity, and Factor H were determined.