title: Observer variability in ECG interpretation for thrombolysis eligibility: experience and context matter.
abstract: BACKGROUND
  Despite the known benefit of thrombolysis it remains underutilized among eligible patients with acute myocardial infarction. We sought to determine whether potential errors in ECG interpretation might be a contributing factor and to what extent clinical history, a checklist outlining recognized inclusion criteria and a computerized interpretation would influence reliability and accuracy.
  
  
  METHODS
  Seventy-five ECGs were interpreted on 8 separate occasions by 9 clinicians (3 cardiologists, 3 cardiology fellows, 3 medical residents) according to a 2 x 2 x 2 factorial design.
  
  
  RESULTS
  The overall level of agreement among all raters was substantial with a kappa (kappa) of 70.4%. Intra-observer ECG reading reliability was stronger among cardiologists (CC) as compared with cardiology fellows (CF) and medical residents (MR). Similarly, inter-observer reliability was substantial to very good and a gradient was seen with greater reliability among CC, followed by CF, then MR ( P = 0.0013). CC recommended thrombolysis significantly more frequently ( p < 0.001) than either CF or MR. Trainees were biased by the presence of a computerized ECG interpretation resulting in a decision to recommend thrombolysis administration less often.
  
  
  CONCLUSIONS
  The reliability of ECG interpretation for deciding to administer thrombolysis was substantial; there was a gradient from lowest to highest commensurate with training and experience. Errors in thrombolysis eligibility are influenced by clinical history and the presence of a computerized ECG interpretation among less experienced clinicians.
authors.affiliation: Department of Medicine, London Health Sciences Centre, University of Western Ontario, Room 205 Colborne Building, Victoria Campus, 375 South Street, London, Ontario, Canada N6A 4G5. dmassel@lhsc.on.ca
authors.forename: David
authors.initials: D
authors.lastname: Massel
mesh_terms: D003253:Consultants; D003657:Decision Making; D003936:Diagnosis, Computer-Assisted; D003951:Diagnostic Errors; D004562:Electrocardiography / Q000592:standards*; D006801:Humans; D008503:Medical Staff; D015588:Observer Variation; D018579:Patient Selection; D015912:Thrombolytic Therapy / Q000706:statistics & numerical data*