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

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Abstract

PURPOSE: Thrombotic thrombocytopenic purpura and hemolytic uremic syndrome are uncommon disorders that are generally fatal if left untreated. Plasma exchange therapy is associated with high response rates and improved short-term 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 patients with thrombotic thrombocytopenic purpura/hemolytic uremic syndrome, most of whom were treated principally with plasma exchange at the Sacramento Medical Foundation Blood Center and the University of California Davis Medical Center between 1978 and 1998. We measured the effect of therapeutic plasma exchange on 30-day mortality, response rate, and overall survival, and determined which factors were associated with 30-day mortality and relapse.

RESULTS: The overall 30-day mortality was 10% of the 122 patients who received plasma exchange as their principal treatment (a median of 9 exchanges and a mean cumulative infused volume of 43 ± 77 L fresh frozen plasma); 56% were complete responders and 21% were partial responders. The relapse rate was 13%. The estimated 2-year survival was about 60%; among patients without serious underlying comorbid conditions, the estimated 2-year survival 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 ratio = 0.2; 95% CI: 0.03 to 0.9).

CONCLUSION: Plasma exchange therapy produced high response and survival rates in this large cohort of patients with thrombotic thrombocytopenic purpura/hemolytic uremic syndrome. The Clinical Severity Score may be useful in predicting 30-day mortality, whereas fever at onset was associated with a lesser risk of relapse. Prospective studies should stratify patients according to these prognostic factors.

Section snippets

Study sample

The study sample included consecutive patients with TTP or hemolytic uremic syndrome of all ages who were referred to the therapeutic apheresis service of the Sacramento Medical Foundation Blood Center (a not-for-profit community blood center that serves 41 hospitals in a 17-county area of Northern California with an estimated 2.8 million residents) and the University of California Davis Medical Center from 1978 through 1998. The vast majority of patients referred for treatment were seen in the

Results

Of the 126 patients, 95 (75%) had TTP, while the remainder had the hemolytic uremic syndrome. About two thirds of the patients were female, with an age range from 1.5 to 85 years (Table 2). Their ethnic distribution reflected the demographic characteristics of our region. About 30% of patients had an underlying serious medical disorder. The median platelet count was 29,000/μL, with a range from 7,000 to 121,000/μL; the median hemoglobin level was 9.1 g/dL with a range of 2.8 to 15.6 g/dL. The

Discussion

We studied the effects of early, aggressive plasma exchange in the management of TTP and the hemolytic uremic syndrome. The overall response rate of 77% is remarkably similar to the 76% response to plasma exchange that was reported in a 1982 review (16). The observed 30-day mortality of 10% is comparable with the mortality rate of 9% reported by Bell et al (17), although in that series, all deaths occurred within 4 days of diagnosis and not all patients received plasma exchange therapy. In the

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Supported in part by a grant from the US Public Health Service (HL 55181).

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