A review of randomized controlled trials using therapeutic apheresis*
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Apheresis has developed into a common therapeutic modality. The evidence for the clinical benefit of apheresis, however, is generally from uncontrolled and nonrandomized trials. Although the effectiveness of therapeutic apheresis may be established from uncontrolled trials, well-designed, randomized controlled trials provide the best evidence for a clinical benefit because this type of trial design minimizes bias. We assess the evidence for the use of apheresis, the optimal schedules for apheresis, and the replacement solutions used, based on randomized controlled trials. The databases, MEDLINE and EMBASE, and reference lists from relevant articles were searched. The literature search was restricted to articles published in English and included adult patients only. Two of the authors (NS, CK) independently reviewed the citation list to identify reports for retrieval, and the kappa statistic was used to quantify agreement between the reviewers. Articles were included if they used apheresis as an intervention and had clinical endpoints. The quality of the studies was assessed by using a validated instrument. Five hundred and ninety-two citations were identified, and a total of 85 reports were included in this review. There are only a few well-established indications for therapeutic apheresis. Randomized, controlled trials have clearly shown a benefit for patients treated with apheresis who have Guillain-Barre syndrome and patients who have thrombotic thrombocytopenic purpura. A clinical benefit has not been shown for a variety of conditions, including systematic lupus erythematosus, polyarteritis nodosa/Churg-Strauss syndrome, and for the treatment of renal allograft rejection. The effectiveness of apheresis needs to be clarified for several other diseases. As better-designed, randomized trials are performed, the role of apheresis for these indications will be further elucidated.