Improved survival with plasma exchange in patients with thrombotic thrombocytopenic purpura-hemolytic uremic syndrome

PURPOSE: Thrombotic thrombocytopenic purpura and hemolytic uremic syndrome are uncommon disorders that are generally fatal if left untreated. Plasma e xchange therapy is associated with high response rates and improved short-t erm survival, but most previous studies have been limited by small numbers of patients or short duration of follow-up. METHODS: We performed a retrospective cohort analysis in 126 consecutive pa tients with thrombotic thrombocytopenic purpura/hemolytic uremic syndrome, most of whom were treated principally with plasma exchange at the Sacrament o Medical Foundation Blood Center and the University of California Davis Me dical Center between 1978 and 1998. We measured the effect of therapeutic p lasma exchange on 30-day mortality, response rate, and overall survival, an d determined which factors were associated with 30-day mortality and relaps e. RESULTS: The overall 30-day mortality was 10% of the 122 patients who recei ved plasma exchange as their principal treatment (a median of 9 exchanges a nd a mean cumulative infused volume of 43 +/- 77 L fresh frozen plasma); 56 % were complete responders and 21% were partial responders. The relapse rat e was 13%. The estimated 2-year survival was about 60%; among ne. patients without serious underlying comorbid conditions, the estimated 2-year surviv al was about 80%. Each unit increase in clinical severity score (on a 0 to 8 scale) was associated with a 2.2-fold (95% confidence interval [CI]: 1.3 to 3.9) increase in the odds of 30-day mortality. Patients who were febrile at presentation were substantially less likely to suffer a relapse (odds r atio = 0.2; 95% CI: 0.03 to 0.9). CONCLUSION: Plasma exchange therapy produced high response and survival rat es in this large cohort of patients with thrombotic thrombocytopenic purpur a/hemolycic uremic syndrome. The Clinical Severity Score may be useful in p redicting 30-day mortality, whereas fever at onset was associated with a le sser risk of relapse. Prospective studies should stratify patients accordin g to these prognostic factors. Am J Med. 1999;107: 573-579. (C) 1999 by Exc erpta Medica, Inc.