Published: 14 March 2020
Authors: Aparna Balasubramanian, MD Todd M. Kolb, MD, PhD Rachel L. Damico, MD, PhD Paul M. Hassoun, MD Meredith C. McCormack, MD Stephen C. Mathai, MD
Source: This abstract has been sourced from NZ Respiratory Research Review Issue 180
Patients with COPD who experience pulmonary hypertension (PH) have worse mortality than those with COPD alone. Predictors of poor outcomes in COPD-PH are not well-described. Diffusing capacity of the lung (D lco) assesses the integrity of the alveolar-capillary interface and thus may be a useful prognostic tool among those with COPD-PH.
Using a single center registry, we sought to evaluate D lco as a predictor of mortality in a cohort of patients with COPD-PH.
This retrospective cohort study analyzed 71 COPD-PH patients from the Johns Hopkins Pulmonary Hypertension Registry with right-sided heart catheterization (RHC)-proven PH and pulmonary function testing data within one year of diagnostic RHC. Transplant-free survival was calculated from index RHC. Adjusted transplant-free survival was modelled using Cox proportional hazard methods; age, pulmonary vascular resistance, FEV 1, oxygen use, and N-terminal pro-brain natriuretic peptide were included as covariates.
Overall unadjusted transplant-free 1-, 3-, and 5-year survivals were 87%, 60%, and 51%, respectively. Survival was associated with reduced D lco across the observed range of pulmonary artery pressures and pulmonary vascular resistance. Severe D lco impairment was associated with poorer survival (log-rank χ 2 13.07) ( P < .001); adjusting for covariates, for every percent predicted decrease in D lco, mortality rates increased by 4% (hazard ratio, 1.04; 95% CI, 1.01-1.07).
Among patients with COPD-PH, severe gas transfer impairment is associated with higher mortality, even with adjustment for airflow obstruction and hemodynamics, which suggests that D lco may be a useful prognostic marker in this population. Future studies are needed to further investigate the association between D lco and morbidity and to determine the utility of D lco as a biomarker for disease risk and severity in COPD-PH.
