PURPOSE: In order to accurately assess exercise interventions and to evaluate acute and chronic cardiovascular effects in patients with early-stage cancer, consistently reliable functional outcome measures must be obtained.
An incremental cardiopulmonary exercise test (CPET) with gas exchange measurement, to assess peak oxygen consumption (peak VO2), provides the gold standard outcome of cardiorespiratory fitness.
METHODS: In the context of a randomized controlled trial, 40 prostate cancer patients (mean age 59±7 years) following radical prostatectomy performed two maximal CPETs within 5.6±5.5 days of each other. Incremental treadmill tests were performed in the morning under identical laboratory conditions. Reliability and within subject variability from test 1 to test 2 for peak and submaximal variables were assessed by correlation coefficients, intraclass correlations (ICC), Bland-Altman plots, coefficient of variation (CV), and paired t-tests.
RESULTS: There was high reliability between CPETs for peak VO2 (r=0.92, p< 0.001, ICC=0.900); ventilatory threshold (VT; r=0.88, p< 0.001, ICC=0.927); minute ventilation-carbon dioxide production relationship (VE/VCO2; r=0.86, p < 0.001, ICC=0.850); and peak heart rate (HR; r=0.95, p< 0.001, ICC=0.944). However, high within-subject variability was observed for all CPET parameters (mean coefficient of variation: 4.7%). Compared to test 1, significantly higher mean values were observed for peak VO2 (27.0±5.6 vs. 28.1±5.3 mLkgmin, p< 0.05), VT (1.91±0.5 vs. 1.97±0.4 Lmin, p< 0.05) and VE/VCO2: (31.3±5.8 vs. 32.8±3.4, p< 0.05) in test 2.
CONCLUSION: These findings indicate the presence of significant, and potentially clinically important, variability in CPET procedures in men with clinically-localized prostate cancer, and have important implications for the application and utility of CPETs to evaluate the efficacy of interventions to improve aerobic capacity in the oncology setting.
Written by:
Scott JM, Hornsby WE, Lane A, Kenjale AA, Eves ND, Jones LW. Are you the author?
Universities Space Research Association, Houston, Texas, USA; Duke University Medical Center, Durham, North Carolina, USA; Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada; Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
Reference: Med Sci Sports Exerc. 2014 Apr 28. Epub ahead of print.
PubMed Abstract
PMID: 24781891
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