UNITED-STATES THROMBOTIC THROMBOCYTOPENIC PURPURA APHERESIS STUDY-GROUP (US TTP ASG) - MULTICENTER SURVEY AND RETROSPECTIVE ANALYSIS OF CURRENT EFFICACY OF THERAPEUTIC PLASMA-EXCHANGE

Thrombotic thrombocytopenic purpura (TTP) remains enigmatic from the p erspective of its etiology, pathophysiology, and treatment. Once recog nized, the accepted standard of care for TTP is daily therapeutic plas ma exchange (TPE). However, the diversity in TPE treatment protocols h as made comparisons of clinical research between institutions difficul t. This study strived to assess the current practice of TPE in order t o provide direction for prospective controlled clinical trials. Twenty large apheresis centers within the United States comprising the US TT P ASG responded to a survey to establish the current status of TPE in TTP. A retrospective analysis from data provided by 14 of 20 centers i ncluded 115 initial presentations of primary TTP with an overall morta lity rate of 10% and relapse rate of 37%. The majority of deaths (58%) occurred within 48 hours of presentation. Variation in therapeutic ta rgets (platelet count [plt] and serum LDH) and the number of plasma vo lumes exchanged per procedure did not affect the relapse rate. Initial pit and LDH were not predictive of mortality. Response, relapse, and mortality rates with the combination of 5% albumin for the initial 50% of TPE followed by plasma for the final 50% of TPE as replacement wer e comparable or possibly better than plasma-only replacement strategie s. Forty percent of centers routinely used a TPE taper; however, there was no statistical difference in relapse rates comparing the taper an d non-taper sub-groups. By controlling for adjunctive modalities such as steroids and anti-platelet agents, it is hoped that future prospect ive clinical trials may optimize the role of TPE in TTP, minimize pati ent exposure to blood products and procedures, shorten the clinical co urse of TTP, and reduce mortality. (C) 1998 Wiley-Liss,Inc.