title: Interoperator and intraoperator variability of whole blood coagulation assays: a comparison of thromboelastography and rotational thromboelastometry.
abstract: OBJECTIVE
  Near-patient viscoelastic tests have proved useful in decreasing blood and blood product use in cardiac surgery. Two different analyzers are available, TEG and ROTEM. Many different individuals operate these devices, which raises concern that this factor may significantly affect results. The present study sought to objectively assess variability in results between operators.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Regional cardiac center.
  
  
  METHODS
  Adult patients undergoing elective cardiac surgery.
  
  
  METHODS
  Thirty-six mL of blood were taken from each of 21 patients. TEG kaolin and functional fibrinogen (FF) analyses and the equivalent ROTEM INTEM S and FIBTEM S analyses were performed. Six operators performed one of each test per patient to assess interoperator variability. One further operator performed 6 of each test per patient to assess intraoperator variability.
  
  
  RESULTS
  All routine measurement parameters were noted and the coefficient of variation (CV) calculated, analyzing comparable parameters. All inter-operator CVs were significantly lower for ROTEM analyses compared with TEG. CV for INTEM S CT/ kaolin r time was 4.7 versus 16.3 and MCF/MA was 2.6 versus 4.3 (p < 0.01). Similarly, FIBTEM S MCF/ FF MA was 8.3 versus 12.2. All intraoperator CVs were significantly lower for ROTEM analyses compared with TEG (p<0.01). CV for INTEM S CT/kaolin r time was 3.1 versus 9.8 and MCF/ MA was 1.6 versus 4. Similarly, FIBTEM S MCF/ MA was 6.9 versus 12.1.
  
  
  CONCLUSIONS
  This series of results suggested ROTEM analyses are more reproducible than TEG and, consequently, that ROTEM may be better suited for use in a multiuser environment.
authors.affiliation: Department of Anesthesia, Golden Jubilee National Hospital, Clydebank, Scotland. Electronic address: Lynne.Anderson@gjnh.scot.nhs.uk.
authors.forename: Lynne
authors.initials: L
authors.lastname: Anderson
authors.affiliation: Department of Anesthesia, Golden Jubilee National Hospital, Clydebank, Scotland.
authors.forename: Isma
authors.initials: I
authors.lastname: Quasim
authors.affiliation: Department of Anesthesia, Golden Jubilee National Hospital, Clydebank, Scotland.
authors.forename: Mark
authors.initials: M
authors.lastname: Steven
authors.affiliation: Department of Anesthesia, Golden Jubilee National Hospital, Clydebank, Scotland.
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Moise
authors.affiliation: Department of Anesthesia, Golden Jubilee National Hospital, Clydebank, Scotland; University of Glasgow Academic Unit of Anaesthesia, Glasgow. Scotland.
authors.forename: Ben
authors.initials: B
authors.lastname: Shelley
authors.affiliation: Department of Anesthesia, Golden Jubilee National Hospital, Clydebank, Scotland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schraag
authors.affiliation: Department of Anesthesia, Golden Jubilee National Hospital, Clydebank, Scotland.
authors.forename: Andrew
authors.initials: A
authors.lastname: Sinclair
mesh_terms: D000328:Adult; D001777:Blood Coagulation; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D011446:Prospective Studies; D015203:Reproducibility of Results; D013916:Thrombelastography / Q000379:methods* / Q000592:standards* / Q000706:statistics & numerical data
keywords: interindividual variation; near-patient testing; thromboelastography; thromboelastometry