Categorization and impact of pulmonary hypertension in patients with advanced COPD

Introduction: The functional significance of pulmonary hypertension (PH) in COPD is unclear. The purpose of the study was to define the prevalence, severity and associated functional impact of PH in patients with severe COPD listed for lung transplant. Methods: A retrospective review of the Organ Procurement and Tissue Network (OPTN) database between 1997 and 2006 for patients with the primary diagnosis of COPD. Baseline demographics, hemodynamics, pulmonary function tests, six minute walk distance test (6MWD) and pre-transplant survival data was analyzed. Results: 4930 patients with COPD had evaluable right heart catheterization data (RHC). PH was present in 30.4%, with pulmonary venous hypertension (PVH) accounting for an additional 17.2% of patients. Patients with pulmonary hypertension walked an average of 28 m less than those with normal hemodynamics. Normal hemodynamics group: 261 ± 104 m, PH; 238 ± 106 m (p < 0.01), PVH: 228 ± 104 m (p < 0.05). In a multivariable analysis, the mean pulmonary artery pressure (β = -1.33; p = 0.01) was an independent predictor of a reduced 6MWD, as were forced vital capacity (β = 1.48; p < 0.001) and patient age (β = -1.91; p < 0.001). Both PH (HR 1.23 95%CI [1.01-1.50]) and PVH (HR 1.35 95%CI [1.11-1.65]) were shown to be independent risk factors for mortality on the waiting list, even after adjustment for age sex, race, BMI, lung function, severity of illness and diabetes (PH: HR 1.27; 95%CI [1.04-1.55], PVH: HR 1.40; 95%CI [1.13-1.73]). Conclusion: PH is common in advanced COPD and is associated with functional impairment and an increased mortality risk. Stratification by RHC determined pulmonary hemodynamics appears important in distinguishing distinct clinical phenotypes.