Pulmonary Hypertension as a Prognostic Indicator at the Initial Evaluation in Idiopathic Pulmonary Fibrosis

Abstract

Background: The impact of pulmonary hypertension (PH) on survival has been demonstrated in severe cases with idiopathic pulmonary fibrosis (IPF) who were referred for transplantation. However, whether PH is a predictor of survival remains unclear in milder cases. Objectives: To evaluate the survival impact of pulmonary artery pressure measured during the initial evaluation in patients with IPF. Methods: We retrospectively analyzed the initial evaluation data of 101 consecutive IPF patients undergoing right heart catheterization. Patients evaluated with supplemental oxygen were excluded. Predictors of 5-year survival were analyzed using the Cox proportional model. Results: The mean forced vital capacity (FVC) % predicted, diffusing capacity of the lung for carbon monoxide (D<smlcap>LCO</smlcap>) % predicted, and mean pulmonary artery pressure (MPAP) were 70.2 ± 20.1%, 47.9 ± 19.5%, and 19.2 ± 6.5 mm Hg, respectively. A univariate Cox proportional hazard model showed that the body mass index, %FVC, %D<smlcap>LCO</smlcap>, baseline Pa<smlcap>O</smlcap>₂, modified Medical Research Council score, 6-min walk distance, and lowest Sp<smlcap>O</smlcap>₂ of the 6-min walk test were significantly predictive of survival. The MPAP and pulmonary vascular resistance of right heart catheterization were also significant. With stepwise, multivariate Cox proportional analysis, MPAP (HR = 1.064; 95% CI 1.015-1.116, p = 0.010) and %FVC (HR = 0.965, 95% CI 0.949-0.982, p < 0.001) were independent determinants of survival. Analysis of the receiver operating curve revealed MPAP >20 mm Hg to be optimal for predicting the prognosis. Conclusions: Higher MPAP and lower %FVC at the initial evaluation were significant independent prognostic factors of IPF. The current results suggested the importance of the initial evaluation of PH for patients with IPF.