Functional associations of pleuroparenchymal fibroelastosis and emphysema with hypersensitivity pneumonitis.

Joseph Jacob,Claudio Macaluso,Elisabetta Renzoni,Sujal Desai,Athol U Wells,Angelo De Lauretis,Anne Laure Brun,Maria Kokosi,Anand Devaraj,Arlette Odink

doi:10.1016/j.rmed.2018.03.031

Abstract

BACKGROUNDPleuroparenchymal fibroelastosis (PPFE) has been described in hypersensitivity pneumonitis (HP) yet its functional implications are unclear. Combined pulmonary fibrosis and emphysema (CPFE) has occasionally been described in never-smokers with HP, but epidemiological data regarding its prevalence is sparse. CTs in a large HP cohort were therefore examined to identify the prevalence and effects of PPFE and emphysema.Methods233 HP patients had CT extents of interstitial lung disease (ILD) and emphysema quantified to the nearest 5%. Lobar percentage pleural involvement of PPFE was quantified on a 4-point categorical scale: 0 = absent, 1 = affecting <10%, 2 = affecting 10–33%, 3 = affecting >33%. Marked PPFE reflected a total lung score of ≥3/18. Results were evaluated against FVC, DLco and mortality.RESULTSMarked PPFE prevalence was 23% whilst 23% of never-smokers had emphysema. Following adjustment for patient age, gender, smoking status, and ILD and emphysema extents, marked PPFE independently linked to reduced baseline FVC (p = 0.0002) and DLco (p = 0.002) and when examined alongside the same covariates, independently linked to worsened survival (p = 0.01).CPFE in HP demonstrated a characteristic functional profile of artificial lung volume preservation and disproportionate DLco reduction. CPFE did not demonstrate a worsened outcome when compared to HP patients without emphysema beyond that explained by CT extents of ILD and emphysema.CONCLUSIONSPPFE is not uncommon in HP, and is independently associated with impaired lung function and increased mortality. Emphysema was identified in 23% of HP never-smokers. CPFE appears not to link to a malignant microvascular phenotype as outcome is explained by ILD and emphysema extents.

Highlights

Over the past fifteen years, the existence of idiopathic pleuroparenchymal fibroelastosis (PPFE) has been increasingly recognised [1,2], and in 2013, PPFE was included in the consensus classification of the idiopathic interstitial pneumonias [3]
Combined pulmonary fibrosis and emphysema (CPFE) did not demonstrate a worsened outcome when compared to hypersensitivity pneumonitis (HP) patients without emphysema beyond that explained by CT extents of interstitial lung disease (ILD) and emphysema
Marked PPFE was identified in 23% of HP patients and was independently associated with a reduced forced vital capacity (FVC) and DLco, and, importantly, was independently predictive of mortality

Summary

Introduction

Over the past fifteen years, the existence of idiopathic pleuroparenchymal fibroelastosis (PPFE) has been increasingly recognised [1,2], and in 2013, PPFE was included in the consensus classification of the idiopathic interstitial pneumonias [3]. Non-idiopathic PPFE has been increasingly reported in association with several interstitial lung diseases (ILD) including idiopathic pulmonary fibrosis (IPF) [2,4,5], hypersensitivity pneumonitis (HP) [2,6] and familial forms of pulmonary fibrosis [1,7]. Our study aimed to characterize the prevalence and functional and prognostic effects of emphysema and PPFE identified on CT imaging in a large population of patients with hypersensitivity pneumonitis. Following adjustment for patient age, gender, smoking status, and ILD and emphysema extents, marked PPFE independently linked to reduced baseline FVC (p = 0.0002) and DLco (p = 0.002) and when examined alongside the same covariates, independently linked to worsened survival (p = 0.01)

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