title: Late relapses in patients successfully treated for thrombotic thrombocytopenic purpura. Canadian Apheresis Group.
abstract: OBJECTIVE
  To determine the incidence and timing of relapses in patients who have recovered from an acute episode of thrombotic thrombocytopenic purpura.
  
  
  METHODS
  Clinical follow-up for 3 to 10 years.
  
  
  METHODS
  General community outpatient study; patients who had relapse were hospitalized.
  
  
  METHODS
  63 of 72 surviving patients who had participated in a randomized study that compared plasma exchange and plasma infusion as treatments for thrombotic thrombocytopenic purpura and for whom continued clinical follow-up was obtained.
  
  
  METHODS
  Recurrence of thrombotic thrombocytopenic purpura as defined by a decrease in platelet count to less than 100 x 10(9)/L and by the onset of microangiopathic hemolytic anemia as identified by erythrocyte fragmentation in a peripheral blood film.
  
  
  RESULTS
  37 of the 63 patients have not had recurrence of thrombotic thrombocytopenic purpura and have remained completely well; 6 patients have not had recurrence but have developed other medical problems; 3 patients have not had recurrence but have residual neurologic defects from the original episode; and 17 patients have had one or more recurrences, occurring 7 months to 8 years after the original episode. As determined by Kaplan-Meier analysis, the projected recurrence rate after 10 years in all surviving patients is 36% (95% CI, 23% to 59%).
  
  
  CONCLUSIONS
  More than one third of patients who survive an acute episode of thrombotic thrombocytopenic purpura will have at least one relapse during the following 10 years.
authors.affiliation: University of Toronto, Canada.
authors.forename: K H
authors.initials: KH
authors.lastname: Shumak
authors.forename: G A
authors.initials: GA
authors.lastname: Rock
authors.forename: R C
authors.initials: RC
authors.lastname: Nair
mesh_terms: D000328:Adult; D001803:Blood Transfusion; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010951:Plasma Exchange; D010976:Platelet Count; D011697:Purpura, Thrombotic Thrombocytopenic / Q000628:therapy*; D012008:Recurrence; D013997:Time Factors; D016896:Treatment Outcome