title: A pilot study to assess the utility of five established variables to standardize exercise treadmill test reporting.
abstract: BACKGROUND
  The prognostic utility of 5 established variables (functional capacity, Duke treadmill score, chronotropic response to exercise, heart rate recovery, and premature ventricular contractions) together after routine exercise treadmill testing (ETT) has not been determined.
  
  
  METHODS
  We assessed the combined prognostic ability of 5 established variables for the primary outcome (myocardial infarction [MI], coronary revascularization [CR] or all-cause mortality) and the secondary outcome of unnecessary downstream testing (defined as receipt of further noninvasive imaging without CR, MI, or death) compared with standard methods. Using a retrospective study design, 1857 consecutive patients were enrolled in the year 2014 and followed until December 31, 2015. Optimal discrimination and global fit statistics were assessed from logistic regression models. Classification and regression tree (CART) methodology was used for the final model.
  
  
  RESULTS
  The mean [SD] age was 56.0 [12.5]years; median comorbidities (2, IQR 2) with 26% having an equivocal report. Compared to other models, a model with age, sex, and the 5 established variables showed an improvement in discrimination for the primary [c-statistic 0.85 versus (0.69-0.79)] and secondary [c-statistic 0.73 versus (0.65-0.71)] outcomes with substantial improvement in global fit. The final, optimal, 10-fold cross-validated CART model had a c-statistic of 0.78.
  
  
  CONCLUSIONS
  The utility of the 5-established variables, based on the current study, resides in its ability to decrease unnecessary downstream testing and improve cardiovascular event prognostication. This is accomplished by removing the subjective interpretation of currently used ETT variables that can lead to an equivocal report.
authors.affiliation: Division of Cardiology, Kaiser Permanente, San Jose, CA, United States; Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, United States. Electronic address: ashok.krishnaswami@kp.org.
authors.forename: Ashok
authors.initials: A
authors.lastname: Krishnaswami
authors.affiliation: Department of Hospital Medicine, Kaiser Permanente, San Jose, CA, United States.
authors.forename: William K W
authors.initials: WK
authors.lastname: Ho
authors.affiliation: Division of Nuclear Medicine, Kaiser Permanente, San Jose, CA, United States.
authors.forename: Walter P
authors.initials: WP
authors.lastname: Kwan
authors.affiliation: Department of Hospital Medicine, Kaiser Permanente, San Jose, CA, United States.
authors.forename: Christine
authors.initials: C
authors.lastname: Tsou
authors.affiliation: Division of Cardiology, Kaiser Permanente, Oakland, CA, United States; Division of Research, Kaiser Permanente Division of Research, Oakland, CA, United States.
authors.forename: Jamal S
authors.initials: JS
authors.lastname: Rana
authors.affiliation: Division of Cardiology, Kaiser Permanente, Oakland, CA, United States; Division of Research, Kaiser Permanente Division of Research, Oakland, CA, United States; Stanford University School of Medicine, Stanford, CA, United States.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Solomon
authors.affiliation: Division of Research, Kaiser Permanente Division of Research, Oakland, CA, United States.
authors.forename: Sheng-Fang
authors.initials: SF
authors.lastname: Jiang
authors.affiliation: Division of Cardiology, Kaiser Permanente, San Jose, CA, United States.
authors.forename: James J
authors.initials: JJ
authors.lastname: Jang
authors.affiliation: Division of Cardiology, Kaiser Permanente, San Jose, CA, United States.
authors.forename: Thomas
authors.initials: T
authors.lastname: Alloggiamento
authors.affiliation: Division of Cardiology, Kaiser Permanente, San Jose, CA, United States.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Praserthdam
mesh_terms: D002140:California / Q000453:epidemiology; D002423:Cause of Death; D004562:Electrocardiography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods*; D005260:Female; D055991:Health Records, Personal; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology; D010865:Pilot Projects; D011237:Predictive Value of Tests; D020127:Recovery of Function / Q000502:physiology*; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends
keywords: Death; Electrocardiogram; Myocardial infarction; Prediction; Revascularization; Stress testing