Effect of pulmonary hypertension on exercise tolerance in patients with COPD: A prognostic systematic review and meta-analysis

Background Pulmonary hypertension (PH) is a frequent complication in patients with COPD. Objective To determine if, in patients with COPD, the presence of PH decreases exercise tolerance. Methods We included studies that analysed exercise tolerance using a cardiopulmonary exercise test (CPET) in patients with COPD with PH (COPD-PH) and without PH (COPD-nonPH). Two independent reviewers analysed the studies, extracted the data and assessed the quality of the evidence. Results Of the 4915 articles initially identified, seven reported 257 patients with COPD-PH and 404 patients with COPD-nonPH. The COPD-PH group showed differences in peak oxygen consumption (V’O2peak), -3.09 mL·kg-1·min-1 (95% CI -4.74 to -1.43, p=0.0003); maximum workload (Wmax), -20.5 W (95% CI -34.4 to -6.5, p=0.004); and oxygen pulse (O2 pulse), -1.24 mL·beat-1 (95% CI -2.40 to -0.09, p=0.03), in comparison to the group with COPD-nonPH. If we excluded studies with lung transplant candidates, the sensitivity analyses showed even bigger differences: V’O2, -4.26 mL·min-1·kg-1 (95% CI -5.50 to -3.02 mL·kg-1·min-1, p<0.00001); Wmax, -26.6 W (95% CI -32.1 to -21.1 W, p<0.00001); and O2 pulse, -2.04 mL·beat-1 (95% CI -2.92 to -1.15 mL·beat-1, p<0.0001). Conclusion Exercise tolerance was significantly lower in patients with COPD-PH than in patients with COPD-nonPH, particularly in nontransplant candidates.