Low DLCO in Idiopathic Pulmonary Arterial Hypertension—Clinical Correlates and Prognostic Significance

Abstract

Introduction: Decreased diffusing capacity of the lung for carbon monoxide (DLCO) is observed in some idiopathic pulmonary arterial hypertension (IPAH) patients, but its clinical significance is uncertain. We aimed to assess clinical correlates and prognostic significance of low DLCO in IPAH patients. Material and methods:In the group of 65 IPAH patients the cut off value for low DLCO was set up based on histogram as < 55% of predicted value. Demographic data, exercise capacity, lung function tests, hemodynamic parameters and survival of the patients were compared depending on DLCO value. Results: Low DLCO was found in 18% of the patients, and it was associated with male sex, older age, worse functional status and exercise capacity, and higher prevalence of coronary artery disease. Low DLCO carried a 4-fold increase of death risk in 5-year perspective. Conclusions: Low DLCO was a marker of worse functional capacity and increased risk of death in studied IPAH patients.

The prognostic value of DLCO and pulmonary blood flow in patients with pulmonary hypertension

“…found an increased mortality in idiopathic PAH patients with an DLCO <55% predicted. 21 Kang et al. described a low DLCO as poor prognostic factor in patients with PAH associated with connective tissue disease.…”

“…20 Szturmowicz et al found an increased mortality in idiopathic PAH patients with an DLCO <55% predicted. 21 Kang et al described a low DLCO as poor prognostic factor in patients with PAH associated with connective tissue disease. 22 Hoeper et al found a significantly worse survival rate in patients with PH due to heart failure with preserved ejection fraction and DLCO <45% predicted.…”

Use of supplemental oxygen in patients with pulmonary arterial hypertension in REVEAL

“…A particular focus of the study was the subgroup of patients with severe DLCO reduction, because reduced DLCO has been associated with lower oxygen saturation 19 and a greater likelihood of death in PAH. [13][14][15][16] In a retrospective study of Group 1 PAH patients (n ¼ 408), the risk of death was approximately 2.4 times greater for patients with DLCO values in the lowest tertile for the study population. 14 Kaplan-Meier estimates of survival in patients with (A) normal or mild DLCO reduction (≥60% of predicted), (B) moderate DLCO reduction (40% to o60% of predicted), and (C) severe DLCO reduction (o40% of predicted), according to supplemental oxygen usage.…”

“…idiopathic PAH (n ¼ 65), DLCO of o55% of predicted was associated with a 4-fold greater risk of death within 5 years. 15 Reduced DLCO has also been shown to predict mortality in patients with pulmonary hypertension, resulting from heart failure with preserved ejection fraction. 20,21 Among patients in the severe DLCO reduction subgroup in our study, there was less disparity in prognostic factors and measures of disease severity than in the overall population.…”

“…Reduced diffusing capacity of lung carbon monoxide (DLCO) is a frequent finding in patients with PAH and is associated with an increased risk of death in this population. [13][14][15][16] Patients with PAH and reduced DLCO have reduced resting oxygen saturation compared to those with higher DLCO, 16 making information about supplemental oxygen use of particular interest in patients with lower DLCO and PAH.…”