title: Children and adults with thrombotic thrombocytopenic purpura associated with severe, acquired Adamts13 deficiency: comparison of incidence, demographic and clinical features.
abstract: BACKGROUND
  Thrombotic thrombocytopenic purpura (TTP) associated with severe, acquired ADAMTS13 deficiency is uncommonly reported in children. The incidence, demographic, and clinical features of these children, compared to adults, have not been described.
  
  
  METHODS
  This study focused on children (<18 years old) and adults with TTP associated with severe, acquired ADAMTS13 deficiency, defined as activity <10%. The incidence rates for TTP in children and adults were calculated from patients enrolled in the Oklahoma TTP-HUS (Hemolytic-Uremic syndrome) Registry, 1996-2012. To describe demographic and clinical features, children with TTP were also identified from a systematic review of published reports and from samples sent to a reference laboratory for analysis of ADAMTS13.
  
  
  RESULTS
  The standardized annual incidence rate of TTP in children was 0.09 × 10(6) children per year, 3% of the incidence rate among adults (2.88 × 10(6) adults per year). Among the 79 children who were identified (one from the Oklahoma Registry, 55 from published reports, 23 from the reference laboratory), TTP appeared to be more common among females, similar to the relative increased frequency of women among adults with TTP, and more common in older children. Clinical data were available on 52 children; the frequency of severe renal failure, relapse, treatment with rituximab, and systemic lupus erythematosus in these children was similar to adults with TTP.
  
  
  CONCLUSIONS
  TTP associated with severe, acquired ADAMTS13 deficiency is uncommon in children. The demographic and clinical features of these children are similar to the features of adults with TTP.
authors.affiliation: Department of Biostatistics and Epidemiology, College of Public Health, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73126-0901, USA.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Reese
authors.forename: Darrshini S
authors.initials: DS
authors.lastname: Muthurajah
authors.forename: Johanna A
authors.initials: JA
authors.lastname: Kremer Hovinga
authors.forename: Sara K
authors.initials: SK
authors.lastname: Vesely
authors.forename: Deirdra R
authors.initials: DR
authors.lastname: Terrell
authors.forename: James N
authors.initials: JN
authors.lastname: George
mesh_terms: D051722:ADAM Proteins / Q000097:blood / Q000172:deficiency*; D000071120:ADAMTS13 Protein; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D058846:Antibodies, Monoclonal, Murine-Derived / Q000008:administration & dosage; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007155:Immunologic Factors / Q000008:administration & dosage; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000178:diet therapy / Q000453:epidemiology; D008297:Male; D011697:Purpura, Thrombotic Thrombocytopenic / Q000097:blood / Q000188:drug therapy / Q000453:epidemiology*; D012008:Recurrence; D012042:Registries; D051437:Renal Insufficiency / Q000097:blood / Q000453:epidemiology / Q000628:therapy; D012189:Retrospective Studies; D000069283:Rituximab; D012737:Sex Factors
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D007155:Immunologic Factors; D000069283:Rituximab; D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human
keywords: TTP; children; disparities; incidence; thrombotic thrombocytopenic purpura