title: Effect of ADAMTS13 activity turnaround time on plasma utilization for suspected thrombotic thrombocytopenic purpura.
abstract: BACKGROUND
  Thrombotic thrombocytopenic purpura (TTP) due to deficiency of the von Willebrand-cleaving protease ADAMTS13 is a hematologic emergency that requires prompt initiation of therapeutic plasma exchange (TPE). Long turnaround times (TATs) have precluded the use of pre-TPE measurement of ADAMTS13 activity for the initial diagnosis in most institutions.
  
  
  METHODS
  An in-house rapid TAT (r-TAT) assay for ADAMTS13 activity was implemented after 18 months of validation. In a quasi-experimental design using interrupted time series analysis, patterns of plasma utilization in patients with suspected TTP were assessed after implementation of this assay for ADAMTS13 activity and compared to utilization patterns for patients who received plasma exchange before r-TAT assay implementation designated the standard TAT period.
  
  
  RESULTS
  In the 18 months after implementation of the r-TAT ADAMTS13 assay, there was a significant reduction in plasma utilization per patient suspected of having TTP (mean, 144.5 units vs. 63.3 units of plasma per patients suspected of having TTP; p = 0.002). The mean number of exchanges per patient and mean number of exchanges after achieving a platelet count of at least 150 × 10(9) /L were lower in the r-TAT cohort (p < 0.001 for both). There was no significant difference in 30-day mortality.
  
  
  CONCLUSIONS
  Implementation of a rapid turnaround assay for ADAMTS13 resulted in a significant reduction in plasma utilization for patients with suspected TTP, without an increase in mortality. This study demonstrates that these data, provided in a timely fashion, can avoid unnecessary plasma exchange in patients who do not have TTP.
authors.affiliation: Hematology Division, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Nathan T
authors.initials: NT
authors.lastname: Connell
authors.affiliation: Department of Pathology & Laboratory Medicine, Rhode Island Hospital, Providence, Rhode Island.
authors.forename: Tracey
authors.initials: T
authors.lastname: Cheves
authors.affiliation: Department of Pathology & Laboratory Medicine, Rhode Island Hospital, Providence, Rhode Island.
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Sweeney
mesh_terms: D051722:ADAM Proteins / Q000097:blood*; D000071120:ADAMTS13 Protein; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010951:Plasma Exchange; D011697:Purpura, Thrombotic Thrombocytopenic / Q000097:blood* / Q000401:mortality / Q000628:therapy*
chemical_list: D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human