Abstract
BackgroundChronic hypersensitivity pneumonitis (CHP) has a variable disease course. Computer analysis of CT features was used to identify a subset of CHP patients with an outcome similar to patients with idiopathic pulmonary fibrosis (IPF).MethodsConsecutive patients with a multi-disciplinary team diagnosis of CHP (n = 116) had pulmonary function tests (FEV1, FVC, DLco, Kco, and a composite physiologic index [CPI]) and CT variables predictive of mortality evaluated by analysing visual and computer-based (CALIPER) parenchymal features: total interstitial lung disease (ILD) extent, honeycombing, reticular pattern, ground glass opacities, pulmonary vessel volume (PVV), emphysema, and traction bronchiectasis. Mean survival was compared between both CHP and IPF patients (n = 185).ResultsIn CHP, visual/CALIPER measures of reticular pattern, honeycombing, visual traction bronchiectasis, and CALIPER ILD extent were predictive of mortality (p < 0 · 05) on univariate analysis. PVV was strongly predictive of mortality on univariate (p < 0 · 0001) and multivariate analysis independent of age, gender and disease severity (represented by the CPI [p < 0 · 01]). CHP patients with a PVV threshold >6 · 5% of the lung had a mean survival (35 · 3 ± 6 · 1 months; n = 20/116 [17%]) and rate of disease progression that closely matched IPF patients (38 · 4 ± 2 · 2 months; n = 185).ConclusionsPulmonary vessel volume can identify CHP patients at risk of aggressive disease and a poor IPF-like prognosis.
Highlights
Chronic hypersensitivity pneumonitis (CHP) has a variable disease course
Within the population of chronic hypersensitivity pneumonitis (CHP) patients, it has been observed that some patients may show an accelerated rate of progression, comparable to the trajectory of idiopathic pulmonary fibrosis (IPF) [2, 4, 5]
Demographic data The initial study population, which has not been previously described, comprised 129 consecutive patients newly presenting with an multi-disciplinary team (MDT) diagnosis of CHP based on a compatible clinical history and review of the following data: antigen exposure history, precipitating antibodies, bronchoalveolar lavage (BAL) findings, Computed tomography (CT) imaging (129/129 [100%] of patients), and histopathology (60/129 [46%] of patients)
Summary
Chronic hypersensitivity pneumonitis (CHP) has a variable disease course. Computer analysis of CT features was used to identify a subset of CHP patients with an outcome similar to patients with idiopathic pulmonary fibrosis (IPF). The majority of patients with hypersensitivity pneumonitis who present to specialist centres have the chronic fibrotic form of the disease [1,2,3]. Within the population of chronic hypersensitivity pneumonitis (CHP) patients, it has been observed that some patients may show an accelerated rate of progression, comparable to the trajectory of idiopathic pulmonary fibrosis (IPF) [2, 4, 5]. Given the varied outcome and unpredictable prognosis in CHP, the American National Heart, Lung and Blood Institute, in collaboration with the Office of Rare Diseases, convened a workshop in 2005 to discuss future research priorities in HP [8]. The workshop emphasized the desirability of exploring quantitative CT analysis in longitudinal studies of HP patients [8]
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