Plasmapheresis in thrombotic microangiopathy-associated syndromes: review of outcome data derived from clinical trials and open studies. von Baeyer H. Therapeutic Apheresis 2002;6(4):320-328.

ABSTRACT:

Current reimbursement policy of health insurance for therapeutic plasmapheresis requires proof of efficacy using the concept of evidence-based medicine. The aim of this paper is to review the outcome of plasmapheresis used to treat thrombotic microangiopathy (TMA)-associated syndromes in the last decade to provide scientific evidence to back up reimbursement applications. The strength of evidence of each reviewed study was assessed using the five levels of evidence criteria as defined by the American Society of Hematology in 1996 for assessment of the treatment of immune thrombocytopenia. The level Experimental indication was added for situations where only case reports or small series supported by pathophysiological reasoning are available. The definitions of evidence used in this paper are as follows: Level I, randomized clinical trial with low rates of error; Level II, randomized clinical trial with high rates of error; Level III, nonrandomized studies with concurrent control group; Level IV, nonrandomized studies with historical control group; Level V, case series without a control group or expert opinion; and Experimental, case reports and pathophysiological reasoning. The results of this analysis based on the published data is summarized as follows: The indication of plasmapheresis is assigned to Level IV evidence for primary and secondary thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS); cancer/chemotherapy-associated TTP/HUS is assigned to Level V evidence; and TTP/HUS refractory to standard plasma exchange and post-bone marrow transplantation TTP/HUS are assigned to Experimental indication. For the latter two subsets, protein A immunoadsorption is reportedly successful. Plasmapheresis is not recommended in other TMA-associated syndromes, including HUS in early childhood. Two randomized clinical trials were performed in order to demonstrate the superiority of plasma exchange/fresh frozen plasma (PE/FFP) over plasma transfusion in the management of TTP/HUS. The results prove the greater clinical success of PE/FFP. Standard PE/FFP has reduced the mortality of TTP/HUS from 94.5% to 13%.