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′(O(2peak))), −3.09 mL·kg(−1)·min(−1) (95% CI −4.74 to −1.43, p=0.0003); maximum workload (W(max)), −20.5 W (95% CI −34.4 to −6.5, p=0.004); and oxygen pulse (O(2) 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′(O(2)), −4.26 mL·min(−1)·kg(−1) (95% CI −5.50 to −3.02 mL·kg(−1)·min(−1), p<0.00001); W(max), −26.6 W (95% CI −32.1 to −21.1 W, p<0.00001); and O(2) 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.