Using Cardiopulmonary Exercise Testing Parameters in Predicting COPD Survival

Peak oxygen uptake (VO₂peak) is associated with survival in COPD patients and is a useful measure for assessing severity of chronic obstructive pulmonary disease (COPD). These were among the findings of a retrospective, multicenter, cohort study recently published in Clinical Investigations.

The study authors maintained that VO₂peak is a proxy for cardiopulmonary exercise capacity. Moreover, they noted, although previous research indicates that physical activity significantly influences survival and disease course in COPD, few existing COPD prognostic indices include cardiopulmonary exercise testing (CPET) parameters. This is true even of BODE, a COPD prognostic index integrating measures of body mass index, obstruction (FEV₁), dyspnea [measured via the modified Medical Research Council dyspnea scale], and exercise capacity [measured via 6 minute walking distance test).

In the current study, the researchers analyzed the prognostic value of VO₂peak, as measured via cardiopulmonary exercise testing (CPET), by retrospectively assessing the medical records of 312 outpatients with COPD who underwent CPET between 2004 and 2017. The analysis assessed the relationship between patients’ survival rates and CPET parameters, as well as a range of additional factors including demographics, smoking habits, exacerbation frequency, dyspnea score, lung function measurements, and Global Initiative for Chronic Obstructive Lung Disease (GOLD) categories and scores.

 The analysis found that patients’ 5-year survival probability was 75% and the 10-year survival probability was 75%, and that VO₂peak significantly predicted survival (hazard ratio [HR]: 0.886). The optimal VO₂peak threshold for the 5-year survival was 14.6 mL/kg/min. GOLD category status also influenced survival rates; in GOLD categories A/B, 5-year survival in patients with a VO₂peak of less than 14.6 mL/kg/min vs those with a VO₂peak of 14.6 mL/kg/min or more were 60% vs 86%, respectively, whereas in GOLD categories C/D those survival rates were 64% vs 90%, respectively.

Notably, the GOLD 2020 recommendations suggest the assessment of COPD severity based on spirometry classification (GOLD grades I-IV) along with categorization based on history of moderate/severe exacerbations (GOLD categories A–D). In consideration of future prospective studies, the authors suggest adding VO₂peak to these recommendations.

The investigators concluded that VO₂peak is a highly significant predictor of survival in patients with COPD. “Our data support the incorporation of this surrogate marker of impaired cardiopulmonary capacity into the clinical assessment of patients with COPD alongside established markers (FEV1, exacerbation frequency, and symptoms).”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures

Reference

Ewert R, Obst A, Mühle A, et al. Value of cardiopulmonary exercise testing in the prognosis assessment of chronic obstructive pulmonary disease patients: a retrospective, multicentre cohort study. Respiration. Published online November 19, 2021. doi:10.1159/000519750