BACKGROUND Patients with chronic obstructive pulmonary disease (COPD) who develop 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 (DLCO) assesses the integrity of the alveolar-capillary interface and thus may be a useful prognostic tool among those with COPD-PH. RESEARCH QUESTION Using a single center registry, we sought to evaluate DLCO as a predictor of mortality in a cohort of COPD-PH patients. STUDY DESIGN AND METHODS This retrospective cohort study analyzed 71 COPD-PH patients from the Johns Hopkins Pulmonary Hypertension Registry with right heart catheterization (RHC)-proven PH and pulmonary function testing (PFT) data within 1 year of diagnostic RHC. Transplant-free survival was calculated from index RHC. Adjusted transplant-free survival was modelled using Cox proportional hazard methods, with age, pulmonary vascular resistance (PVR), FEV1, oxygen use, and N-terminal pro-brain natriuretic peptide (NT-proBNP) included as covariates. RESULTS Overall unadjusted transplant-free 1-, 3-, and 5-year survival was 87%, 60%, and 51% respectively. Survival was associated with reduced DLCO across the observed range of pulmonary artery pressures and PVR. Severe DLCO impairment was associated with poorer survival (log-rank ꭕ2 13.07, p<0.001), and adjusting for covariates, for every percent predicted decrease in DLCO, mortality increased by 4% (HR 1.04; 95% CI:1.01-1.07). INTERPRETATION Among patients with COPD-PH, severe gas transfer impairment is associated with higher mortality, even when adjusting for airflow obstruction and hemodynamics, suggesting that DLCO may be a useful prognostic marker in this population. Future studies are needed to further investigate the association between DLCO and morbidity, and to determine the utility of DLCO as a biomarker for disease risk and severity in COPD-PH.

中文翻译：

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弥散能力是与慢性阻塞性肺疾病相关的肺动脉高压结果的独立预测因子


背景 慢性阻塞性肺疾病（COPD）并发肺动脉高压（PH）的患者比单纯患有慢性阻塞性肺疾病（COPD）的患者死亡率更高。 COPD-PH 不良结局的预测因素尚未得到很好的描述。肺弥散能力 (DLCO) 可评估肺泡-毛细血管界面的完整性，因此可能是 COPD-PH 患者的有用预后工具。研究问题 使用单一中心登记处，我们试图评估 DLCO 作为 COPD-PH 患者队列死亡率的预测因子。研究设计和方法 这项回顾性队列研究分析了来自约翰霍普金斯大学肺动脉高压登记处的 71 名 COPD-PH 患者，这些患者在诊断 RHC 后 1 年内拥有经右心导管插入术 (RHC) 证实的 PH 和肺功能测试 (PFT) 数据。根据 RHC 指数计算无移植存活率。使用 Cox 比例风险法对调整后的无移植生存进行建模，其中年龄、肺血管阻力 (PVR)、FEV1、耗氧量和 N 末端脑钠肽前体 (NT-proBNP) 作为协变量。结果 总体未经调整的免移植 1 年、3 年和 5 年生存率分别为 87%、60% 和 51%。在观察到的肺动脉压力和 PVR 范围内，生存与 DLCO 的减少相关。严重的 DLCO 损伤与较差的生存率相关（对数秩 ꭕ2 13.07，p<0.001），并且调整协变量，预计 DLCO 每减少 1%，死亡率就会增加 4%（HR 1.04；95% CI：1.01-） 1.07）。解释 在 COPD-PH 患者中，严重的气体传输障碍与较高的死亡率相关，即使在调整气流阻塞和血流动力学后也是如此，这表明 DLCO 可能是该人群中有用的预后标志物。 未来的研究需要进一步调查 DLCO 与发病率之间的关联，并确定 DLCO 作为 COPD-PH 疾病风险和严重程度的生物标志物的效用。