Antigen Identification and Avoidance on Outcomes in Fibrotic Hypersensitivity Pneumonitis

Assessment of clinical relevance of antigen improves diagnostic accuracy of hypersensitivity pneumonitis

BACKGROUND

Exposure assessment is integral to the diagnosis of hypersensitivity pneumonitis (HP). Although the clinical relevance of exposed antigens is essential for the assessment, many of the previous guidelines or reports have only evaluated simple exposure histories or immunological tests. To overcome this problem, the Exposure Assessment Form (EAF) was developed as an assessment tool for classifying the exposure grade from G0 to G4. The EAF was modified from the description in the Japanese clinical practice guide 2022 for HP published by the Japanese Respiratory Society.

METHODS

One hundred and seventy-two consecutive patients with interstitial lung disease who underwent multidisciplinary discussion (MDD) at our hospital were retrospectively examined. We assessed whether the use of the EAF improved the diagnostic performance of the international guideline of HP. We also evaluated whether the exposure grade affected the prognosis of HP.

RESULTS

Even when a HP diagnosis was made with a confidence of 70% or higher according to the international guideline, less than half of these cases resulted in a final diagnosis of HP when the exposure grades were lower than G3. When the result of the EAF was integrated into the exposure definition of the international guideline, the specificity of the diagnostic performance improved, while sensitivity was maintained. Furthermore, HP patients with an exposure grade of G3 or higher showed a tendency to take a longer time to initiate medication.

CONCLUSIONS

This is the first study to evaluate the clinical relevance of possible antigens using the EAF. Assessing the exposure grade prevents overdiagnosis and improves the diagnostic performance of the international guideline.

Rationale and design of the prognostic transcriptomic signature in fibrotic hypersensitivity pneumonitis (PREDICT) study

Hypersensitivity pneumonitis is an immunologically mediated form of lung disease, resulting from inhalational exposure to a large variety of antigens. A subgroup of patients with fibrotic hypersensitivity pneumonitis (FHP) develop symptomatic, functional and radiographic disease progression. Mortality occurs primarily from respiratory failure as a result of progressive and self-sustaining lung injury that often occurs despite immunosuppression and removal of the inciting antigen. The development and validation of a prognostic transcriptomic signature for FHP (PREDICT-HP) is an observational multicentre cohort study designed to explore a transcriptomic signature from peripheral blood mononuclear cells in patients with FHP that is predictive of disease progression. This article describes the design and rationale of the PREDICT-HP study. This study will enrol ∼135 patients with FHP at approximately seven academic medical sites. Participants with a confirmed diagnosis of FHP are followed over 24 months and undergo physical examinations, self-administered questionnaires, chest computed tomography, pulmonary function tests, a 6-min walk test and blood testing for transcriptomic analyses. At each 6-month follow-up visit the study will assess the participants' clinical course and clinical events including hospitalisations and respiratory exacerbations. The PREDICT study has the potential to enhance our ability to predict disease progression and fundamentally advance our understanding of the pathobiology of FHP disease progression.

Impact of antigen identification on transplant free survival in interstitial lung disease

INTRODUCTION

Antigen identification impacts diagnosis as well as prognosis in patients with hypersensitivity pneumonitis. An antigen may also be present in other etiologies of interstitial lung disease, however it is unknown whether identification impacts survival.

METHODS

We evaluated a retrospective cohort in order to determine if antigen identification affects transplant free survival in patients with hypersensitivity pneumonitis, idiopathic pulmonary fibrosis, connective tissue disease interstitial lung disease, and interstitial pneumonia with autoimmune features. Only patients with definite or high probability of hypersensitivity pneumonitis by American Thoracic Society guidelines were included in the analysis.

RESULTS

Transplant free survival was improved with antigen identification in patients with hypersensitivity pneumonitis but not in patients with idiopathic pulmonary fibrosis, connective tissue disease interstitial lung disease, and interstitial pneumonia with autoimmune features.

CONCLUSION

Our study suggests that removal of identified antigen in interstitial lung diseases other than hypersensitivity pneumonitis may not be impactful. Additionally, it further suggests that definitive diagnosis of hypersensitivity pneumonitis with bronchoalveolar lavage and transbronchial biopsy may be beneficial prior to recommending antigen removal.

Pathologic Criteria for the Diagnosis of Usual Interstitial Pneumonia vs Fibrotic Hypersensitivity Pneumonitis in Transbronchial Cryobiopsies

Transbronchial cryobiopsy (TBCB) is increasingly used for the diagnosis of fibrosing interstitial pneumonias, but there are few detailed descriptions of the pathologic findings in such cases. It has been proposed that a combination of patchy fibrosis and fibroblast foci with an absence of alternative features is diagnostic of usual interstitial pneumonia (UIP; ie, idiopathic pulmonary fibrosis [IPF]) in TBCB. In this study, we reviewed 121 TBCB in which a diagnosis of fibrotic hypersensitivity pneumonitis (FHP; n = 83) or IPF (n = 38) was made by multidisciplinary discussion and evaluated a range of pathologic features. Patchy fibrosis was found in 65 of 83 (78%) biopsies from FHP and 32of 38 (84%) biopsies from UIP/IPF cases. Fibroblast foci were present in 47 of 83 (57%) FHP and 27 of 38 (71%) UIP/IPF cases. Fibroblast foci/patchy fibrosis combined did not favor either diagnosis. Architectural distortion was seen in 54 of 83 (65%) FHP and 32 of 38 (84%) UIP/IPF cases (odds ratio [OR] for FHP, 0.35; P = .036) and honeycombing in 18 of 83 (22%) and 17 of 38 (45%), respectively (OR, 0.37; P = .014). Airspace giant cells/granulomas were present in 13 of 83 (20%) FHP and 1 of 38 (2.6%) UIP/IPF cases (OR for FHP, 6.87; P = .068), and interstitial giant cells/granulomas in 20 of 83 (24%) FHP and 0 of 38 (0%) UIP/IPF (OR, 6.7 x 106; P = .000). We conclude that patchy fibrosis plus fibroblast foci can be found in TBCB from both FHP and UIP/IPF. The complete absence of architectural distortion/honeycombing favors a diagnosis of FHP, as does the presence of airspace or interstitial giant cells/granulomas, but these measures are insensitive, and many cases of FHP cannot be separated from UIP/IPF on TBCB.

Progressive fibrotic interstitial lung disease

Many interstitial lung diseases (ILDs) share mechanisms that result in a progressive fibrosing phenotype. In Brazil, the most common progressive fibrosing interstitial lung diseases (PF-ILDs) are chronic hypersensitivity pneumonitis, idiopathic pulmonary fibrosis, unclassified ILD, and connective tissue diseases. PF-ILD is seen in approximately 30% of patients with ILD. Because PF-ILD is characterized by disease progression after initiation of appropriate treatment, a diagnosis of the disease resulting in fibrosis is critical. Different criteria have been proposed to define progressive disease, including worsening respiratory symptoms, lung function decline, and radiological evidence of disease progression. Although the time elapsed between diagnosis and progression varies, progression can occur at any time after diagnosis. Several factors indicate an increased risk of progression and death. In the last few years, antifibrotic drugs used in patients with idiopathic pulmonary fibrosis have been tested in patients with PF-ILD. The effects of nintedanib and placebo have been compared in patients with PF-ILD, a mean difference of 107.0 mL/year being observed, favoring nintedanib. The U.S. Food and Drug Administration and the Brazilian Health Regulatory Agency have approved the use of nintedanib in such patients on the basis of this finding. Pirfenidone has been evaluated in patients with unclassified ILD and in patients with other ILDs, the results being similar to those for nintedanib. More studies are needed in order to identify markers of increased risk of progression in patients with ILD and determine the likelihood of response to treatment with standard or new drugs.

Contemporary Concise Review 2022: Interstitial lung disease

Novel genetic associations for idiopathic pulmonary fibrosis (IPF) risk have been identified. Common genetic variants associated with IPF are also associated with chronic hypersensitivity pneumonitis. The characterization of underlying mechanisms, such as pathways involved in myofibroblast differentiation, may reveal targets for future treatments. Newly identified circulating biomarkers are associated with disease progression and mortality. Deep learning and machine learning may increase accuracy in the interpretation of CT scans. Novel treatments have shown benefit in phase 2 clinical trials. Hospitalization with COVID-19 is associated with residual lung abnormalities in a substantial number of patients. Inequalities exist in delivering and accessing interstitial lung disease specialist care.

Treatable traits: a comprehensive precision medicine approach in interstitial lung disease

Interstitial lung disease (ILD) is a diverse group of inflammatory and fibrotic lung conditions causing significant morbidity and mortality. A multitude of factors beyond the lungs influence symptoms, health-related quality of life, disease progression and survival in patients with ILD. Despite an increasing emphasis on multidisciplinary management in ILD, the absence of a framework for assessment and delivery of comprehensive patient care poses challenges in clinical practice. The treatable traits approach is a precision medicine care model that operates on the premise of individualised multidimensional assessment for distinct traits that can be targeted by specific interventions. The potential utility of this approach has been described in airway diseases, but has not been adequately considered in ILD. Given the similar disease heterogeneity and complexity between ILD and airway diseases, we explore the concept and potential application of the treatable traits approach in ILD. A framework of aetiological, pulmonary, extrapulmonary and behavioural and lifestyle treatable traits relevant to clinical care and outcomes for patients with ILD is proposed. We further describe key research directions to evaluate the application of the treatable traits approach towards advancing patient care and health outcomes in ILD.

Importance of and Approach to Taking a History of Exposures to Occupational Respiratory Hazards

Occupational respiratory diseases are caused by exposure to respiratory hazards at work. It is important to document those exposures and whether they are causing or exacerbating disease because these determinations can have important impacts on diagnosis, treatment, job restrictions, and eligibility for benefits. Without investigation, it is easy to miss clinically relevant exposures, especially in those with chronic diseases that can have work and nonwork causes. The first and most important step in identifying exposures to respiratory hazards at work is to take an appropriate history. For efficiency, this is a two-step process. An initial quick screening history is done by asking only a few questions. Follow-up questions are asked if there are positive responses to the screening questions or if an occupational etiology is suspected based on the clinical presentation. Electronic health records have promise for facilitating this process. Follow-up to the screening history may include additional questions, evaluating additional sources of information about workplace exposures, and medical testing. Radiographic findings or tests conducted on noninvasive samples or lung tissue can be used as biomarkers. Online resources can be used to learn more about exposures associated with occupations and industries and to see if investigations evaluating exposures were performed in the patient's own workplace. It is important to adhere to the patient's wishes about contacting the employer. With patient consent, the employer can be an important source of information about exposures and, if a problem exists, has an important role in taking corrective action. Consultation for challenging cases is available from a variety of professional and governmental entities. If a clinician identifies a significant public health issue, such as an occupational disease outbreak, it is important to notify relevant public health authorities so that steps can be taken to prevent additional exposures and appropriately care for those already exposed.

Decreased Survival and Lung Function in Progressive Pulmonary Fibrosis

Background and Objectives: Progressive pulmonary fibrosis (PPF) is a recently described term reserved for patients with fibrotic ILD other than idiopathic pulmonary fibrosis (IPF) with fast clinical deterioration. Here, survival and prognostic biomarkers at the time of diagnosis for PPF are investigated in a fibrotic ILD other than IPF cohort (non-IPF). Materials and Methods: Patients diagnosed during the period of 2012-2018 at the ILD Center of Excellence (St. Antonius Hospital, Nieuwegein, The Netherlands) with a fibrotic ILD were included in this study. The presence of PPF was investigated using the criteria from the updated IPF/PPF guideline during the first year after diagnosis. Logistic regression analysis was used to determine risk factors for PPF. A Kaplan-Meier survival analysis with log-rank test was conducted to analyze survival in patients with and without PPF. Results: This study included 304 non-IPF patients and, for comparison, 379 IPF patients. In non-IPF patients, 146 (46%) fulfilled ≥2 criteria for PPF. These patients had a median transplant-free survival rate of 2.9 ± 0.4 years, which was worse than non-IPF patients without PPF (10.1 ± 1.8 years, p < 0.001). The risk for PPF was increased in patients with FVC < 50% (odds ratio (OR) of 2.50, 95% CI = 1.01-6.17, p = 0.047) or DLCOc ≤ 35% (OR = 2.57, 95% CI = 1.24-5.35, p = 0.011). In the first 3 years after diagnosis, survival in PPF and IPF is the same, while in the following years IPF has a significantly worse survival. Conclusions: The non-IPF cohort with PPF had a significantly worse transplant-free survival compared with the non-IPF cohort without PPF. Independent risk factors for PPF in non-IPF were FVC < 50% and DLCOc ≤ 35%.

Impact of diagnostic guidelines on the diagnosis of hypersensitivity pneumonitis

Introduction

Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease from exposure to environmental antigens. Diagnosing HP could be challenging. The American College of Chest Physicians (CHEST) and American Thoracic Society/Japanese Respiratory Society/and Asociación Latinoamericana del Tórax (ATS/JRS/ALAT) have published diagnostic guidelines in 2021 and 2020 respectively. The CHEST guideline uses four grades of confidence: confident (>90%), provisional high (70-89%), provisional low (51-69%), and unlikely (≤50%). The ATS/JRS/ALAT guideline uses five grades of confidence: definite (>90%), high (80-89%), moderate (70-79%), low (51-69%) and not excluded (≤50%). In this study, we determined how these two guidelines could have affected the diagnosis of HP made before the guidelines.

Methods

Two hundred and fifty-nine adult patients from a previous cohort with HP (ICD-9:495) made between Jan. 1, 2008, and Dec. 31, 2013, at Duke University Medical Center were included. We simplified the diagnostic confidence into three categories so we could compare the guidelines: high (≥90%), intermediate (51-89%), and low (≤50%).

Results

There were 156 female and 103 male. Mean age was 58 (range: 20-90). 68.8% of the patients had restrictive defects (FVC < 80% pred) and 48.6% had lung biopsy. The CHEST guideline classified 33.6% of the patients into high, 59.5% into intermediate and 6.9% into low confidence categories. The ATS/JRS/ALAT guideline classified 29.7% of the patients into high, 21.2% into intermediate and 49.0% into low confidence categories (p < 0.0001 vs. CHEST). Cohen's kappa was 0.331. In patients with identifiable inciting agents (IAs) (N = 168), the CHEST guideline classified 32.1% of the patients into high, 64.3% into intermediate and 3.6% into low confidence categories. The ATS/JRS/ALAT guideline classified 29.2% of the patients into high, 20.8% into intermediate, and 50.0% into low confidence categories. Cohen's kappa was 0.314.

Discussion

In our HP cohort with two-thirds of the patients with restrictive defects, we found the two guidelines had fair agreement in diagnosing HP with or without identifiable IAs. They agreed more when the diagnostic confidence was high. When the diagnostic confidence was lower, however, the ATS/JRS/ALAT guideline was more stringent. Clinicians should be aware of the differences between the two guidelines when evaluating patients suspicious of HP.

Clusters of comorbidities in fibrotic hypersensitivity pneumonitis

BACKGROUND

Hypersensitivity pneumonitis (HP) is a type of interstitial lung disease (ILD) with a variable disease course and prognosis ranging from inflammatory and self-limiting to irreversible and progressive pulmonary fibrosis. Comorbidities are common in HP and may have an impact on prognosis. Due to the heterogeneity of HP presentation and progression, the identification of specific phenotypes in relationship to disease course and outcome is essential. The aim of this study was to identify clusters of comorbidities which could represent phenotypes in fibrotic HP and examine their impact on prognosis.

METHODS

Patients diagnosed with fibrotic HP at a tertiary referral center for ILD were included. Comorbidities were systematically registered and clusters of comorbidities were identified using cluster analyses. Disease progression and survival was estimated for each cluster.

RESULTS

The cohort comprised 211 patients with 53.6% males, mean age 63.0, baseline FVC 72.7%, DLCO 44.1%. Median follow-up time was 1.8 years (IQR 0.7-3.9). Three clusters with distinct comorbidity profiles and clinical characteristics were identified. One cluster dominated by elder male patients with predominantly cardiovascular diseases was associated with more respiratory hospitalizations and a worse prognosis. Differences in pulmonary function or exercise capacity trajectories between clusters were not observed.

CONCLUSIONS

Three clusters with distinct comorbidities were identified and could represent phenotypes in fibrotic HP not previously recognized. The worst prognosis was observed in a cluster dominated by elder males with cardiovascular diseases. Increased focus on prevention and treatment of comorbidities could potentially improve the prognosis of patients with fibrotic HP.