Prognostic value of key variables from cardiopulmonary exercise testing in patients with COPD: 42-month follow-up

Abstract

Aim

To identify better predictors of early death in patients with chronic obstructive pulmonary disease (COPD) using potential predictors derived from key measures obtained from cardiopulmonary exercise testing (CPET). Methods

This is a prospective, cohort study with 42-month follow-up in 126 COPD patients. Every patient completed the clinical evaluation, followed by a pulmonary function test and CPET. CPET was performed on a cycle ergometer with electromagnetic braking and ventilatory expired analysis was measured breath-by-breath using a computer-based system. Peak oxygen consumption (V̇O2, mlO2. kg−1. min−1), minute ventilation/carbon dioxide production and the, minute ventilation (V̇E, L/min), and the V̇E/carbon dioxide production (V̇E/V̇CO2) slope were obtained from CPET. Results

48 (38%) patients died during the 42-month follow-up. Kaplan Meier analysis revealed a V̇E/V̇CO2 slope ≥30, peak V̇E ≤ 25.7L/min and peak V̇O2 ≤ 13.8 mlO2. kg−1. min−1were strong predictors of mortality in COPD patients. Cox regression revealed that the V̇O2 peak ≤13.8 mlO2. kg−1. min−1 (CI 95% 0.08–0.93), V̇E/V̇CO2 slope ≥30 (CI 95% 0.07–0.94), V̇E peak ≤25.7 L/min (CI 95% 0.01–0.15), Sex (CI 95% 0.04–0.55) and Age (CI 95% 1.03–1.2) were the main predictors of mortality risk. Conclusion

Diminished exercise capacity and peak ventilation as well as ventilatory inefficiency are independent prognostic markers. Similar to patients with heart failure, CPET may be a valuable clinical assessment in the COPD population.