BACKGROUND: Maximal oxygen uptake (VO2max) obtained from incremental exercise testing is a useful indicator of limited exercise capacity. Several prediction equations have been developed to estimate VO2max in patients with chronic obstructive pulmonary disease (COPD), but agreement studies between estimated and measured VO2max are lacking. This study aims to assess agreement between the 6 estimated VO2max equations and direct measures of VO2max evaluated during maximal incremental exercise testing in male COPD patients.
METHODS: Patients with stable COPD, in accordance with GOLD guidelines, were included in the study. Agreement between VO2max obtained during incremental exercise testing and VO2max obtained from 6 prediction equations were studied. To estimate VO2max from anthropometric prediction equations, lung function variables and submaximal exercise testing were used.
RESULTS: Of the 60 male patients in the study, 12 were GOLD stage II, 24 GOLD stage III, and 24 GOLD stage IV. Five prediction equations underestimated the value of VO2max in relation to measured VO2max: equations 1, 2, 3, 4, and 6, by 14%, 66%, 42.2%, 35%, and 23.3%, respectively. Conversely, prediction equation 5 overestimated measured VO2max by 76.9%. Agreement between all VO2max prediction equations and measured VO2max was poor. Discrepancy between VO2max prediction equations and measured VO2max varied from 20.857 to 0.736 L/min.
CONCLUSIONS: The use of lung function at rest and submaximal exercise testing is inaccurate for determining VO2max, which cannot be estimated by prediction equations in patients with stable COPD.