A comparison of maximal oxygen uptake obtained from different tests in chronic obstructive pulmonary disease patients

Background: This study aims to assess the correlation between maximal oxygen uptake (peakVO(2)) during cardiopulmonary exercise test (CPET) and peakVO(2) obtained from incremental shuttle walking test (ISWT) in patients with chronic obstructive pulmonary disease (COPD) and to investigate their relationship with quality of life. Methods: Data of 38 stable COPD patients (35 males, 3 females; mean age 64.6 +/- 8.3 years; range 48 to 82 years) who completed outpatient pulmonary rehabilitation (PR) program and assessed by CPET and ISWT through treadmill test was retrospectively analyzed. Pulmonary rehabilitation was performed during eight weeks. PeakVO(2) measured via breath-by-breath technique during CPET. PeakVO(2) from ISWT distance was calculated by the formula "4.19+ [0.025x ISWT distance]". Borg scale was used for the evaluation of dyspnea severity before and after PR, whereas St. George's Respiratory Questionnaire was used for quality of life. Results: PeakVO(2) on CPET were found 15.9 +/- 5.1 ml/min/kg before PR and 17.3 +/- 5.3 ml/min/kg after PR (p=0.001). The peakVO(2) calculated with ISWT was 11.6 +/- 3.2 ml/min/kg before PR and 13.4 +/- 3.2 ml/min/kg after PR (p<0.001). Incremental shuttle walking test distance increased from 296.1 +/- 128.9 meters to 367.1 +/- 129.1 meters (p<0.001). A significant relationship between peakVO(2) on CPET and calculated peakVO(2) from ISWT before and after PR (p=0.001, p=0.005, respectively). A moderate positive correlation (r=0.50) and a weak correlation (r=0.449) were found before and after PR, respectively. Dyspnea was reduced and quality of life and walking distance were improved after PR. There were significant but weak correlations between activity, impact, total score of St. George's Respiratory Questionnaire and peakVO(2) on CPET before and after PR (p<0.05). Conclusion: Incremental shuttle walking test can also be used for the evaluation of exercise capacity in COPD patients. Although it is an inexpensive and easy-to-use method, CPET should be preferred to achieve objective results.