Idiopathic pleuroparenchymal fibroelastosis: three-dimensional computed tomography assessment of upper-lobe lung volume

Abstract

BackgroundIdiopathic pleuroparenchymal fibroelastosis (iPPFE) is a rare interstitial lung disease characterised by predominant upper lobe fibrosis involving the pleura and subpleural lung parenchyma. Despite its poor prognosis, there is no consensus on prognostic determinants of iPPFE to date. Because volume loss in the upper lobe is a distinct feature of iPPFE, we hypothesised that the lung volume of the bilateral upper lobes (upper lobe-volume) accurately indicates disease severity and mortality risk in iPPFE patients.MethodsThis retrospective study assessed two cohorts of 132 patients with iPPFE (69 in Hamamatsu cohort; 63 in Seirei cohort) and 45 controls. Each lobe volume was quantitatively measured using three-dimensional computed tomography at the time of iPPFE diagnosis and standardised using predicted forced vital capacity.ResultsThe standardised upper lobe-volume was less than twice as small in iPPFE patients versus controls, whereas the lower lobe-volume did not decrease. iPPFE patients with lower standardised upper lobe-volume had significantly shorter survival rates than those with higher volume (median survival: 6.08 versus 2.48 years, p<0.001). In multivariate analysis, the lower standardised upper lobe-volume was significantly associated with increased mortality adjusting for age, sex and forced vital capacity [hazard ratio: 0.939].A composite scoring model, including age, sex and standardised upper lobe volume, was associated with a better risk of death than the gender-age-physiology (GAP) model.ConclusionAssessment of upper lobe-volume provides useful information for managing iPPFE by evaluating disease severity and mortality risk in clinical practice.

Assessment of malnutrition-related risk in patients with idiopathic pleuroparenchymal fibroelastosis

“…Indeed, survival curves for GAP stage II and GAP stage III were completely inverted in the present study. Recently, we reported a separate composite model using age, sex and standardised upper lobe lung volumes measured by 3D-CT [24]. This 3D-CT model achieved excellent prognostic separation with a higher C-index (0.762) in patients with iPPFE.…”

“…To date, several prognostic factors including lower FVC [22][23][24][25], presence of lower lobe ILD [23] and history of pneumothorax [26] have been reported in patients with iPPFE [26]. Recently, we also identi ed upper lobe lung volume measured using 3D-CT and standardised with predicted FVC as a signi cant prognostic factor in patients with iPPFE [24].…”

Assessment of malnutrition-related risk in patients with idiopathic pleuroparenchymal fibroelastosis

“…To date, several prognostic factors including lower FVC [ 27 , 28 , 32 , 33 ], presence of lower lobe ILD [ 28 ] and history of pneumothorax [ 34 ] have been reported in patients with IPPFE [ 34 ]. Recently, we also identified upper lobe lung volume measured using three-dimensional (3D)-CT and standardised with predicted FVC as a significant prognostic factor in patients with IPPFE [ 32 ]. However, the significance of these reported prognostic factors is not fully consistent between previous studies.…”

“…Indeed, survival curves for GAP stage II and GAP stage III were completely inverted in the present study. Recently, we reported a separate composite model using age, sex and standardised upper lobe lung volumes measured by 3D-CT [ 32 ]. This 3D-CT model achieved good prognostic separation with a higher C-index (0.762) in patients with IPPFE.…”

Platythorax increases residual volume/total lung capacity in idiopathic pleuroparenchymal fibroelastosis

“…The quantified lung volumes were standardized by dividing them by the predicted value of forced vital capacity (FVC), as previously described. [13]…”