Abstract
Background: Plasmapheresis is the mainstay of therapy for thrombotic thrombocytopenic purpura (TTP). Due to the significant mortality associated with TTP if left untreated and the effectiveness of therapy, plasmapheresis may be instituted before the diagnosis is clearly established. Our case-control study of incident TTP allowed us to evaluate the incidence of complications in cases treated at multiple sites across the United States.
Methods: The SERF-TTP study is a NHLBI-funded 15-site study to identify 300 cases of incident TTP and 600 age and gender-matched community controls. Each case of incident TTP is identified upon referral for therapeutic plasma exchange (TPE). Exclusion criteria include solid organ or allogeneic stem cell transplant, anti-neoplastic therapy, or metastatic adenocarcinoma. Epidemiologic information, laboratory data, and plasma samples are collected from both patients and controls. In addition, information is collected about volume of TPE, frequency, type of replacement fluid, duration of TPE, adverse reactions associated with TPE, and concurrent therapy.
Results: To date, 11 sites across the US have IRB approval, and 50 cases have been identified. Data are available for the first 32 patients, whose mean age is 41.9 years. All patients underwent TPE, a number of which received more than one type of replacement fluid. The majority of patients received fresh frozen plasma (FFP): 60.0% FFP, 46.7% cyroprecipitate poor plasma, and 16.7% albumin. Additionally, 63.3% of patients received concurrent corticosteroid therapy. The mean number of treatment days prior to the achievement of platelet count > 150,000 per microliter was 9.7 (range 0–43 days). Overall survival was 90.0%. Adverse reactions were observed in 53.3% of patients (16/30). The most frequently observed toxicity was an allergic reaction in 40% (12/30) of patients, followed by citrate-related toxicity in 30% (9/30) of patients. No patients experienced an anaphylactic reaction. 16.7% of cases (5/30) had venous access complications, most frequently a catheter-associated thrombosis (3/5). In addition, one patient had a significant hemorrhage associated with venous access, which required treatment in intensive care.
Conclusions: Preliminary data from this cohort of patients suggest that adverse reactions are commonly seen in incident TTP patients undergoing TPE; the most frequent are allergic reactions to plasma. This highlights the need for development of reliable diagnostic criteria for TTP so patients are not exposed to the risks of TPE unnecessarily.
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