Open AccessLung function and peak oxygen uptake in chronic obstructive pulmonary disease phenotypes with and without emphysema
Author(s) -
Øystein Rasch-Halvorsen,
Erlend Hassel,
Ben Brumpton,
Haldor Jenssen,
Martijn A. Spruit,
Arnulf Langhammer,
Sigurd Steinshamn
Publication year - 2021
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0252386
Subject(s) - copd , medicine , lung volumes , cardiology , pulmonary function testing , obstructive lung disease , lung , spirometry , asthma
Previous studies of associations of forced expiratory lung volume in one second (FEV 1 ) with peak oxygen uptake (VO 2peak ) in chronic obstructive pulmonary disease (COPD) have not taken sex, age and height related variance of dynamic lung volumes into account. Nor have such demographic spread of spirometric measures been considered in studies comparing VO 2peak between COPD phenotypes characterized by degree of emphysema. We aimed to assess the association of FEV 1Z-score with VO 2peak in COPD (n = 186) and investigate whether this association differs between emphysema (E-COPD) and non-emphysema (NE-COPD) phenotypes. Corresponding assessments using standardized percent predicted FEV 1 (ppFEV 1 ) were performed for comparison. Additionally, phenotype related differences in VO 2peak were compared using FEV 1Z-score and ppFEV 1 as alternative expressions of FEV 1 . E-COPD and NE-COPD were defined by transfer factor of the lung for carbon monoxide below and above lower limits of normal (LLN), respectively. The associations were assessed in linear regression models. One unit reduction in FEV 1Z-score was associated with 1.9 (95% CI 1.4, 2.5) ml/kg/min lower VO 2peak . In stratified analyses, corresponding estimates were 2.2 (95% CI 1.4, 2.9) and 1.2 (95% CI 0.2, 2.2) ml/kg/min lower VO 2peak in E-COPD and NE-COPD, respectively. The association did not differ statistically by COPD phenotype (p-value for interaction = 0.153). Similar estimates were obtained in analyses using standardized ppFEV 1 . Compared to NE-COPD, VO 2peak was 2.2 (95% CI 0.8, 3.6) and 2.1 (95% CI 0.8, 3.5) ml/kg/min lower in E-COPD when adjusted for FEV 1Z-score and ppFEV 1 , respectively. In COPD, FEV 1Z-score is positively associated with VO 2peak . This association was stronger in E-COPD but did not differ statistically by phenotype. Both the association of FEV 1 with VO 2peak and the difference in VO 2peak comparing COPD phenotypes seems independent of sex, age and height related variance in FEV 1 . Mechanisms leading to reduction in FEV 1 may contribute to lower VO 2peak in E-COPD.