Chest
Volume 131, Issue 3, March 2007, Pages 650-656
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Original Research: Interstitial Lung Disease
Significance of Pulmonary Arterial Pressure and Diffusion Capacity of the Lung as Prognosticator in Patients With Idiopathic Pulmonary Fibrosis

https://doi.org/10.1378/chest.06-1466Get rights and content

Abstract

Study objectives:To evaluate the long-term clinical course of patients with idiopathic pulmonary fibrosis (IPF) complicated with pulmonary arterial hypertension.

Design:Prospective analysis of consecutive IPF patients undergoing initial workup with right-heart catheterization (RHC) and pulmonary function testing (PFT). Pulmonary arterial pressure (PAP) and diffusion capacity of the lung for carbon monoxide (Dlco) were focused on.

Setting:University hospital.

Patients:Seventy-eight patients with IPF (67 men, 11 women; diagnosis by pathology, n = 59; clinical diagnosis, n = 19) had been followed up after initial workup for a maximum of 14 years.

Measurements and results:RHC data on 61 patients and PFT data on 52 patients were available. Five-year survival rates were 62.2% in the normal-PAP group (mean PAP < 17 mm Hg, n = 37) and 16.7% in the high-PAP group (mean PAP > 17 mm Hg, n = 24) [p < 0.001]; 70.4% in the preserved-Dlcogroup (percentage of predicted > 40%, n = 27) and 20.0% in the low-Dlcogroup (percentage of predicted < 40%, n = 25) [p < 0.001]; and 82.6% in group 1 (normal PAP and preserved Dlco, n = 23) and 15.6% in group 2 (high PAP, low Dlco, or both, n = 32) [p < 0.0001]. The relative risks of mortality within 5 years after RHC were 2.20 (95% confidence interval [CI], 1.40 to 3.45) in the high-PAP group, 2.70 (95% CI, 1.46 to 4.99) in the low-Dlcogroup, and 4.85 (95% CI, 1.97 to 11.97) in group 2.

Conclusion:Dlcowas a critical factor for evaluating disease status and prognosis, and PAP status provided feasible information in the initial workup of IPF patients.

Section snippets

Study Population

Seventy-eight patients with IPF (67 men, 11 women; diagnosis by pathology, n = 59; clinical diagnosis, n = 19) underwent RHC and PFT at their initial workup under normal conditions while breathing room air. None of the patients were receiving corticosteroids or immunosuppressive agents at the time of the initial workup. Three patients who died within a month of open-lung biopsy were excluded from the longitudinal study because the biopsy surgery was judged to have significantly influenced the

Initial Workup

Data on 70 patients were available for analysis of initial workups. Among them, PAH (mPAP > 25 mm Hg) was detected in six patients (8.1%). The mPAP was significantly correlated with both Pao2and %Dlco(r= − 0.470, p < 0.0001, andr= − 0.460, p < 0.001, respectively) [Table 1;Fig 1].

Five-Year Survival

In addition to the three patients who died within a month after open-lung biopsy and the eight patients with diseases other than IPF, six patients were unavailable during the follow-up period. This left data on 61

Discussion

The main focus in this study was to evaluate the influence of elevated PAP on the prognosis of IPF. Among the 70 patients who underwent RHC during their initial workup, the prevalence of PAH based on standard criterion (mPAP > 25 mm Hg) was 8.1% (6 patients). Lettieri et al26reported a markedly higher prevalence of 31.6% among IPF patients who underwent the evaluation while waiting for lung transplantation. In estimations of PAP by Nadrous et al25using the USCG method, systolic PAP was > 50 mm

Acknowledgments

The authors thank their colleagues from the Division of Respiratory Medicine of Kyoto University Hospital for cooperating and collecting patient data, especially Dr. Michio Hayashi, Kobe Central Hospital, who helped with RHC. We also thank Mr. Simon Johnson for working with the language of this article.

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    This work was performed at Kyoto University. Original data from this study were presented at the 100th International Conference of the American Thoracic Society, San Diego, CA, May 22, 2005. This study was funded by a grant from the Ministry of Science and Education in Japan.

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