Authors

1. Fregonezi, Guilherme PT, PhD
2. Resqueti, Vanessa PT, PhD
3. Vigil, Laura MD, PhD
4. Calaf, Nuria ND
5. Casan, Pere MD, PhD

Abstract

BACKGROUND: Maximal oxygen uptake (VO_2max) obtained from incremental exercise testing is a useful indicator of limited exercise capacity. Several prediction equations have been developed to estimate VO_2max in patients with chronic obstructive pulmonary disease (COPD), but agreement studies between estimated and measured VO_2max are lacking. This study aims to assess agreement between the 6 estimated VO_2max equations and direct measures of VO_2max 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 VO_2max obtained during incremental exercise testing and VO_2max obtained from 6 prediction equations were studied. To estimate VO_2max 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 VO_2max in relation to measured VO_2max: equations 1, 2, 3, 4, and 6, by 14%, 66%, 42.2%, 35%, and 23.3%, respectively. Conversely, prediction equation 5 overestimated measured VO_2max by 76.9%. Agreement between all VO_2max prediction equations and measured VO_2max was poor. Discrepancy between VO_2max prediction equations and measured VO_2max 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 VO_2max, which cannot be estimated by prediction equations in patients with stable COPD.