title: Test-Retest Reliability of Maximal and Submaximal Gas Exchange Variables in Patients With Coronary Artery Disease.
abstract: OBJECTIVE
  Gas exchange variables derived from cardiopulmonary exercise tests (CPETs) need to be reliable for evaluating interventions and clinical decision making. Whereas peak oxygen uptake ((Equation is included in full-text article.)O2) has shown to be a highly reliable parameter in patients with coronary artery disease (CAD), little is known about the reproducibility of these parameters in patients with CAD. Therefore, the purpose of this study was to confirm the reliability of peak (Equation is included in full-text article.)O2 and to investigate the reliability of submaximal CPET variables in patients with CAD.
  
  
  METHODS
  Eighty-five patients with CAD (57.6 ± 8.5 years; 79 males) performed 2 CPETs within 10 days before starting a rehabilitation program. Reliability of peak and submaximal exercise variables was assessed by using intraclass correlation coefficients (ICC), coefficients of variation, Pearson correlation coefficients, paired t tests, and Bland-Altman plots.
  
  
  RESULTS
  Maximal and submaximal exercise parameters showed adequate reliability. Overall, there was a good correlation across both testing occasions (r = 0.63-0.95; P < .05 for all). Peak (Equation is included in full-text article.)O2 (ICC, 0.95; 95% CI, 0.92-0.97) demonstrated excellent reliability. Of the submaximal exercise variables, oxygen uptake efficiency slope (OUES) was as reliable as peak (Equation is included in full-text article.)O2 (ICC, 0.97; 95% CI, 0.95-0.98). The ventilation/carbon dioxide production ((Equation is included in full-text article.)E/(Equation is included in full-text article.)CO2) slope showed very good test-retest reliability (ICC, 0.87; 95% CI, 0.80-0.91) and the (Equation is included in full-text article.)O2/work rate slope showed good reliability (ICC, 0.76; 95% CI, 0.64-0.85).
  
  
  CONCLUSIONS
  Both peak (Equation is included in full-text article.)O2 and OUES show excellent test-retest reliability. Accordingly, in the case of no or unreliable peak (Equation is included in full-text article.)O2 data, we suggest using OUES to evaluate cardiorespiratory fitness in patients with CAD.
authors.affiliation: Department of Rehabilitation Sciences (Ms Coeckelberghs, Dr Buys, Ms Pattyn, Dr Vanhees, and Dr Cornelissen), Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Leuven, Belgium; and Department of Cardiovascular Sciences (Dr Goetschalckx), Faculty of Medicine, KU Leuven, Leuven, Belgium.
authors.forename: Ellen
authors.initials: E
authors.lastname: Coeckelberghs
authors.forename: Roselien
authors.initials: R
authors.lastname: Buys
authors.forename: Kaatje
authors.initials: K
authors.lastname: Goetschalckx
authors.forename: Nele
authors.initials: N
authors.lastname: Pattyn
authors.forename: Luc
authors.initials: L
authors.lastname: Vanhees
authors.forename: Véronique
authors.initials: V
authors.lastname: Cornelissen
mesh_terms: D000368:Aged; D003324:Coronary Artery Disease / Q000503:physiopathology*; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D005082:Physical Exertion / Q000502:physiology; D011659:Pulmonary Gas Exchange; D012123:Pulmonary Ventilation; D015203:Reproducibility of Results