title: ADAMTS13 and anti-ADAMTS13 antibodies as markers for recurrence of acquired thrombotic thrombocytopenic purpura during remission.
abstract: BACKGROUND
  From 20 to 50% of patients who survive an acute episode of the acquired form of thrombotic thrombocytopenic purpura relapse but clinical and laboratory markers of recurrence are not well established.
  
  
  METHODS
  In 109 patients enrolled in an international registry we evaluated, in the frame of a retrospective cohort study, the predictive role of the metalloprotease ADAMTS13 as measured in plasma during remission. Anti-ADAMTS13 antibodies and von Willebrand factor were also evaluated in a smaller number of the same patients.
  
  
  RESULTS
  Median values of ADAMTS13 activity and antigen were significantly lower in patients with recurrent thrombotic thrombocytopenic purpura than in those with no recurrence (activity: 12% vs. 41%; p=0.007; antigen: 36% vs. 58%; p=0.003). A severe deficiency of ADAMTS13 activity (10% or less) was associated with a higher likelihood of recurrence (odds ratio 2.9; 95% confidence interval 1.3 to 6.8; p=0.01). Anti-ADAMTS13 antibodies were also more prevalent in patients with recurrent thrombotic thrombocytopenic purpura (odds ratio 3.1; 95% confidence interval 1.4 to 7.3; p=0.006). The presence during remission of both severe ADAMTS13 deficiency and anti-ADAMTS13 antibodies increased the likelihood of recurrence 3.6 times (95% confidence interval 1.4 to 9.0; p=0.006). The presence of ultralarge von Willebrand factor multimers and of associated diseases or conditions did not increase recurrence.
  
  
  CONCLUSIONS
  Survivors of an acute episode of acquired thrombotic thrombocytopenic purpura with severely reduced levels of ADAMTS13 and/or with anti-ADAMTS13 antibodies during remission have an approximately three-fold greater likelihood of developing another episode of thrombotic thrombocytopenic purpura than patients with higher protease activity and no antibody.
authors.affiliation: Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, University of Milan, Department of Medicine and Medical Specialities, IRCCS Maggiore Hospital, Mangiagalli and Regina Elena Foundation, Luigi Villa Foundation, Milan, Italy. flora.peyvandi@unimi.it
authors.forename: Flora
authors.initials: F
authors.lastname: Peyvandi
authors.forename: Silvia
authors.initials: S
authors.lastname: Lavoretano
authors.forename: Roberta
authors.initials: R
authors.lastname: Palla
authors.forename: Hendrik B
authors.initials: HB
authors.lastname: Feys
authors.forename: Karen
authors.initials: K
authors.lastname: Vanhoorelbeke
authors.forename: Tullia
authors.initials: T
authors.lastname: Battaglioli
authors.forename: Carla
authors.initials: C
authors.lastname: Valsecchi
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Canciani
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Fabris
authors.forename: Samo
authors.initials: S
authors.lastname: Zver
authors.forename: Marienn
authors.initials: M
authors.lastname: Réti
authors.forename: Danijela
authors.initials: D
authors.lastname: Mikovic
authors.forename: Mehran
authors.initials: M
authors.lastname: Karimi
authors.forename: Gaetano
authors.initials: G
authors.lastname: Giuffrida
authors.forename: Luca
authors.initials: L
authors.lastname: Laurenti
authors.forename: Pier Mannuccio
authors.initials: PM
authors.lastname: Mannucci
mesh_terms: D051722:ADAM Proteins / Q000097:blood* / Q000276:immunology; D000071120:ADAMTS13 Protein; D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D011697:Purpura, Thrombotic Thrombocytopenic / Q000097:blood* / Q000276:immunology / Q000401:mortality; D012008:Recurrence; D012042:Registries; D012074:Remission Induction; D012189:Retrospective Studies; D012307:Risk Factors; D014841:von Willebrand Factor / Q000032:analysis / Q000276:immunology
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D014841:von Willebrand Factor; D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human