title: Thrombotic thrombocytopenic purpura at the Johns Hopkins Hospital from 1992 to 2008: clinical outcomes and risk factors for relapse.
abstract: BACKGROUND
  Plasma exchange, the standard treatment for thrombotic thrombocytopenic purpura (TTP), has significantly decreased disease mortality. However, TTP recurs in 20% to 50% of patients who survive the initial episode. We aimed to describe the clinical spectrum of TTP, to determine the valid endpoint for plasma exchange cessation, and to explore the risk factors for disease relapse.
  
  
  METHODS
  Using the ICD-9 diagnosis code, we identified patients treated for TTP at the Johns Hopkins Hospital between 1992 and 2008. Complete demographic, clinical, laboratory, treatment, and outcome data were collected from the medical records.
  
  
  RESULTS
  A total of 72 patients were treated for 134 episodes of TTP at the Johns Hopkins Hospital during the study period. With standardized combined immunosuppression and plasma exchange treatment, the all-cause mortality rate was 4%. Lactate dehydrogenase (LDH) normalization lagged behind platelet (PLT) recovery by an average of 9 days and did not predict response. Relapse occurred in 36% of patients during a median follow-up of 30 months with most (76%) occurring in the first 24 months. African American ethnicity was associated with increased risk of relapse (odds ratio = 4.8, p = 0.03).
  
  
  CONCLUSIONS
  Excellent outcomes in patients with TTP are achievable with multimodality therapy. LDH normalization lags behind PLT recovery and might not be an informative endpoint for plasma exchange cessation. Prospective studies are warranted to confirm the influence of race on relapse and identify additional risk factors for adverse outcomes that could be targeted to improve therapeutic outcomes for patients with TTP.
authors.affiliation: Division of Hematology, Department of Medicine, Johns Hopkins University School of Medicine, Ross Research 1032, 720 Rutland Avenue, Baltimore, MD 21205, USA. hzhan1@jhmi.edu
authors.forename: Huichun
authors.initials: H
authors.lastname: Zhan
authors.forename: Michael B
authors.initials: MB
authors.lastname: Streiff
authors.forename: Karen E
authors.initials: KE
authors.lastname: King
authors.forename: Jodi B
authors.initials: JB
authors.lastname: Segal
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001792:Blood Platelets / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D007527:Isoenzymes / Q000097:blood; D007677:Kidney Function Tests; D007770:L-Lactate Dehydrogenase / Q000097:blood; D007902:Length of Stay; D008297:Male; D008396:Maryland; D008875:Middle Aged; D010951:Plasma Exchange; D011697:Purpura, Thrombotic Thrombocytopenic / Q000453:epidemiology* / Q000401:mortality / Q000628:therapy*; D012008:Recurrence; D012307:Risk Factors; D017741:Survivors
chemical_list: D007166:Immunosuppressive Agents; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase