Chest
Volume 138, Issue 4, October 2010, Pages 950-955
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Original Research
Exercise Testing
Reproducibility of Peak Oxygen Uptake and Other Cardiopulmonary Exercise Parameters: Implications for Clinical Trials and Clinical Practice

https://doi.org/10.1378/chest.09-2624Get rights and content

Background

Clinical trialists involved in projects aimed at assessing the impact of a device or therapy on exercise capacity must select an end point that can detect a therapy-derived change and do so in a manner that is both sensitive to the change and valid. Using baseline data from the Prospective Evaluation of Elastic Restraint to Lessen the Effects of Heart Failure (PEERLESS-HF) trial, we describe the coefficient of variation (CV) for peak oxygen uptake (

o2) and other parameters measured during a cardiopulmonary exercise (CPX) test.

Methods

Prior to conducting CPX testing, a CPX core laboratory conducted training with testing staff at each site, and a standardized quality assurance protocol was completed. During screening, subjects performed two symptom-limited CPX tests (CPX-0 and CPX-1) within 14 days.

Results

The CVs for peak

o2, ventilatory efficiency, and ventilatory-derived anaerobic threshold were 5.9%, 4.8%, and 6.8%, respectively. During CPX-0, the percentage of subjects with a respiratory exchange ratio (RER) < 1.05 who increased their peak
o2 by ≥ 6% during CPX-1 was 47%, compared with 12% of subjects also with an RER < 1.05 who experienced a decrease in peak
o2 ≥ 6%.

Conclusions

In a multisite clinical trial setting, we showed that the achieved test-retest reproducibility for peak

o2 can be acceptable, as evidenced by a CV at 5.9%. Until more data are available to identify patients who may demonstrate greater test-retest variance and to avoid repeat testing in all subjects at baseline, clinical trialists might consider repeating tests when RER < 1.05.

Trial registration

clinicaltrials.gov; Identifier: NCT00382863

Section snippets

Subjects

Subjects (N = 160) were screened for the PEERLESS-HF trial sponsored by Paracor Medical, Inc (Sunnyvale, CA). PEERLESS-HF is a randomized trial (35 sites) evaluating a cardiac restraint device (HeartNet; Paracor Medical, Inc), using a primary efficacy composite end point of change in peak

o2, 6-min walk distance, and quality of life at 6 months. Inclusion criteria were age 18-75 years; American College of Cardiology/American Heart Association Stage C; ejection fraction ≤ 35%; and on stable

Results

Demographic and clinical characteristics of subjects screened between November 13, 2006, and June 25, 2009, are shown in Table 1. One hundred sixty subjects had two CPX tests with the same exercise mode within 14 days (mean = 4 ± 4 days). Among CPX-0, 47% (n = 75) were stopped because of symptom-limited fatigue; 35% (n = 56) for shortness of breath; and the balance for dizziness/lightheadedness (n = 5), skeletal-muscular complaints (n = 4), angina (n = 4), or other reasons (n = 16). Data from

Discussion

The use of CPX testing in clinical trials to assess intervention-related changes in cardiorespiratory parameters can be challenging and requires special equipment and staff trained to maintain the equipment and properly conduct the test.7, 8 Like all variables measured during an experiment, the parameters assessed during CPX testing are subject to both physiologic and technical variability. These concerns can be magnified when testing is conducted across dozens of sites. Using staff training

Conclusions

In conclusion, in a multisite clinical trial setting, we showed that the test-retest reproducibility of peak

o2 can be quite acceptable, with a CV of 5.9%. Our data suggest that standardized laboratory and test administration guidelines and training can be employed that allow peak
o2 to be used as a reliable parameter to assess exercise capacity. Finally, until more data are available to identify patients who may demonstrate greater test-retest variance and to avoid repeat testing in all

Acknowledgments

Author contributions: Dr Keteyian: contributed to the coordination and oversight of the exercise testing in which these data originated through functions of the core laboratory, the design of the analysis, data analysis and interpretation, and manuscript preparation.

Mr Brawner: contributed to the coordination and oversight of the exercise testing in which these data originated through functions of the core laboratory, the design of the analysis, data analysis and interpretation, and manuscript

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