The incidence of thrombotic thrombocytopenic purpura-hemolytic uremic syndrome: all patients, idiopathic patients, and patients with severe ADAMTS-13 deficiency

Authors

  • D. R. TERRELL,

    1. Hematology-Oncology Section, Department of Medicine, College of Medicine, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
    2. Department of Biostatistics and Epidemiology, College of Public Health, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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  • L. A. WILLIAMS,

    1. Hematology-Oncology Section, Department of Medicine, College of Medicine, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
    2. Department of Biostatistics and Epidemiology, College of Public Health, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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  • S. K. VESELY,

    1. Department of Biostatistics and Epidemiology, College of Public Health, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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  • B. LÄMMLE,

    1. Central Hematology Laboratory, University Hospital, Inselspital, University of Bern, Bern, Switzerland
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  • J. A. K. HOVINGA,

    1. Central Hematology Laboratory, University Hospital, Inselspital, University of Bern, Bern, Switzerland
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  • J. N. GEORGE

    1. Hematology-Oncology Section, Department of Medicine, College of Medicine, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
    2. Department of Biostatistics and Epidemiology, College of Public Health, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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James N. George, The University of Oklahoma Health Sciences Center, Hematology-Oncology Section, P.O. Box 26901, Oklahoma City, OK 73190, USA.
Tel.: (405) 271-4222; fax: (405) 271-6444; e-mail: james-george@ouhsc.edu

Abstract

Summary. Background: Accurate estimates of the incidence of thrombotic thrombocytopenic purpura (TTP) are important to assess the resources required for current treatments as well as to anticipate the need to develop new treatments. Previous estimates have been indirect and have not reported data on patients with ADAMTS-13 deficiency. Objective: To determine the incidence of patients with TTP-hemolytic uremic syndrome (HUS) in three categories: all patients with clinically suspected TTP-HUS, patients with idiopathic TTP-HUS, and patients with severe ADAMTS-13 deficiency. Methods: Incidence rates were estimated from the Oklahoma TTP-HUS Registry, analyzing all 206 consecutive patients from January 1, 1996 to June 30, 2004 who were treated with plasma exchange for their initial episode of clinically suspected TTP-HUS. ADAMTS-13 activity was measured in 186 (90%) of the 206 patients. Results: The age–sex–race standardized annual incidence rates were 11.29 × 106 (95% CI: 9.70–12.88) for all patients with clinically suspected TTP-HUS; 4.46 × 106 (95% CI: 3.43–5.50) for patients with idiopathic TTP-HUS; and 1.74 × 106 (95% CI: 1.06–2.41) for patients with severe ADAMTS-13 deficiency (<5% activity). In all three categories, the incidence rates were greater for women and for blacks. For patients with severe ADAMTS-13 deficiency, the age–sex standardized incidence rate ratio of blacks to non-blacks was 9.29 (95% CI: 4.33–19.93). Conclusions: Accurate incidence rate estimates for all patients with clinically suspected TTP-HUS, idiopathic TTP-HUS, and TTP associated with severe ADAMTS-13 deficiency have been determined. The greater incidence among women and blacks is comparable with their increased risk for other autoimmune disorders.

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