Predictors of Mortality in Patients with Interstitial Lung Disease-Associated Pulmonary Hypertension

Abstract

Background: Pulmonary hypertension (PH) is a well-established complication in interstitial lung disease (ILD) patients. The aim of this study is to investigate the physiological and hemodynamic parameters that predict mortality in patients with ILD-PH.

Methods: Consecutive ILD patients who underwent right heart catheterization (n = 340) were included. The information analyzed included demographics and physiological and hemodynamic parameters. Cox regression models were used to identify independent predictors of survival.

Results: In total, 96 patients had PH and an additional 56 patients had severe PH. The overall survival of idiopathic pulmonary fibrosis (IPF) patients with PH was significantly worse than the survival of patients with other types of ILD with PH (p < 0.0001 by log-rank analysis). Patients with a reduced diffusing capacity of the lung for carbon monoxide (DLco) (<35% predicted), six-minute walk test final oxygen saturation by pulse oximetry (SpO₂) <88% and pulmonary vascular resistance ≥4.5 Wood units in the ILD-PH cohort had significantly worse survival. IPF diagnosis, forced vital capacity, DLco, systolic pulmonary artery pressure and cardiac index were identified as independent predictors of survival among the ILD-PH cohort.

Conclusions: Patients with ILD-PH have poor prognosis. Physiological and hemodynamic parameters were important factors independently associated with outcome.

Keywords: idiopathic pulmonary fibrosis; interstitial lung disease; pulmonary hypertension; pulmonary vascular resistance; six-minute walk test; survival.

Figure 1

Kaplan–Meier survival estimates for the relationship with (A) interstitial lung disease (ILD) patients with and without pulmonary hypertension (PH), (B) idiopathic pulmonary fibrosis (IPF) patients with and without PH, (C) connective tissue disease (CTD) associated ILD patients with and without PH and (D) sarcoidosis patients with and without PH.

Figure 2

Kaplan–Meier survival estimates for interstitial lung disease (ILD) patients with pulmonary hypertension according to the underlying disease idiopathic pulmonary fibrosis (IPF) (red line), connective tissue disease (CTD) associated ILD (green line) and sarcoidosis (blue line).

Figure 3

Kaplan–Meier survival estimates for the relationship with (A) diffusion capacity of the lung for carbon monoxide (DLco) at a threshold of 35% predicted, (B) six-minute walk test (6MWT) final oxygen saturation by pulse oximetry (SpO₂) at a threshold of 88%, (C) pulmonary vascular resistance (PVR) ≥ 4.5 Wood units (WU) and (D) 6 min walk distance (6MWD) at a threshold of 300 m in interstitial lung disease patients with pulmonary hypertension.