Time of exposure as a prognostic factor in avian hypersensitivity pneumonitis

Hypersensitivity Pneumonitis: Updates in Evaluation, Management, and Ongoing Dilemmas

Hypersensitivity pneumonitis (HP) is a heterogenous disease entity characterized by an aberrant immune response to inhalational antigens. Disease modification hinges on early antigen remediation with a goal to attenuate immune dysregulation. Disease severity and progression are mediated by an interface between degree, type and chronicity of exposure, genetic predisposition, and biochemical properties of the inducing agent. Guidelines have provided a standardized approach; however, decision-making remains with many clinical dilemmas. The delineation of fibrotic and nonfibrotic HP is crucial to identify the differences in clinical trajectories, and further clinical trials are needed to understand optimal therapeutic strategies.

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.

Occupational causes of hypersensitivity pneumonitis: a systematic review and compendium

Background

Hypersensitivity pneumonitis (HP) is caused by a variety of antigens and low-molecular-weight chemicals, often through occupational exposure. Making a diagnosis of HP and identifying a cause are challenging. Cryptogenic cases are frequently reported, and missing or incomplete exposure histories can cause misclassification.

Aims

To provide an evidence-based compendium of sources of exposure and causes of HP for the clinician, through systematic review of medical literature.

Methods

Articles related to HP causative agents and occupational exposure were searched from the databases OVID Medline (1946 to October 2020) and EMBASE (1974 to October 2020). Abstracts and full texts of articles were screened by two reviewers. Data on causative antigens, occupational source of exposure and any associated eponymous name were extracted and grouped according to source of exposure.

Results

A total of 1790 articles were identified, from which 305 articles met the inclusion criteria. An additional 22 articles were identified from citation lists of the selected review articles. Sources of exposure identified for HP were sorted into 14 categories of work (agricultural, plant matter processing, wood, animal-related, foodstuff, food processing, metal processing, polymers, other manufacturing, chemicals, aerosolized water, service, waste and sewage and wind instruments).

Conclusions

This work is a comprehensive list of occupational causative agents and exposures causing HP. Cases are grouped by source of exposure, allowing an immediately accessible compendium of causes for use during occupational exposure assessment, which could also form the basis for a clinical questionnaire.

Diagnosis and Evaluation of Hypersensitivity Pneumonitis: CHEST Guideline and Expert Panel Report

BACKGROUND

The purpose of this analysis is to provide evidence-based and consensus-derived guidance for clinicians to improve individual diagnostic decision-making for hypersensitivity pneumonitis (HP) and decrease diagnostic practice variability.

STUDY DESIGN AND METHODS

Approved panelists developed key questions regarding the diagnosis of HP using the PICO (Population, Intervention, Comparator, Outcome) format. MEDLINE (via PubMed) and the Cochrane Library were systematically searched for relevant literature, which was supplemented by manual searches. References were screened for inclusion, and vetted evaluation tools were used to assess the quality of included studies, to extract data, and to grade the level of evidence supporting each recommendation or statement. The quality of the evidence was assessed using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach. Graded recommendations and ungraded consensus-based statements were drafted and voted on using a modified Delphi technique to achieve consensus. A diagnostic algorithm is provided, using supporting data from the recommendations where possible, along with expert consensus to help physicians gauge the probability of HP.

RESULTS

The systematic review of the literature based on 14 PICO questions resulted in 14 key action statements: 12 evidence-based, graded recommendations and 2 ungraded consensus-based statements. All evidence was of very low quality.

INTERPRETATION

Diagnosis of HP should employ a patient-centered approach and include a multidisciplinary assessment that incorporates the environmental and occupational exposure history and CT pattern to establish diagnostic confidence prior to considering BAL and/or lung biopsy. Criteria are presented to facilitate diagnosis of HP. Additional research is needed on the performance characteristics and generalizability of exposure assessment tools and traditional and new diagnostic tests in modifying clinical decision-making for HP, particularly among those with a provisional diagnosis.

Identification and Remediation of Environmental Exposures in Patients With Interstitial Lung Disease: Evidence Review and Practical Considerations

A relationship between inhalational exposure to materials in the environment and development of interstitial lung disease (ILD) is long recognized. Hypersensitivity pneumonitis is an environmentally -induced diffuse parenchymal lung disease. In addition to hypersensitivity pneumonitis, domestic and occupational exposures have been shown to influence onset and progression of other ILDs, including idiopathic interstitial pneumonias such as idiopathic pulmonary fibrosis. A key component of the clinical evaluation of patients presenting with ILD includes elucidation of a complete exposure history, which may influence diagnostic classification of the ILD as well as its management. Currently, there is no standardized approach to environmental evaluation or remediation of potentially harmful exposures in home or workplace environments for patients with ILD. This review discusses evidence for environmental contributions to ILD pathogenesis and draws on asthma and occupational medicine literature to frame the potential utility of a professional evaluation for environmental factors contributing to the development and progression of ILD. Although several reports suggest benefits of environmental assessment for those with asthma or certain occupational exposures, lack of information about benefits in broader populations may limit application. Determining the feasibility, long-term outcomes, and cost-effectiveness of environmental evaluation and remediation in acute and chronic ILDs should be a focus of future research.

Exposure Assessment Tools for Hypersensitivity Pneumonitis. An Official American Thoracic Society Workshop Report

This report is based on proceedings from the Exposure Assessment Tools for Hypersensitivity Pneumonitis (HP) Workshop, sponsored by the American Thoracic Society, that took place on May 18, 2019, in Dallas, Texas. The workshop was initiated by members from the Environmental, Occupational, and Population Health and Clinical Problems Assemblies of the American Thoracic Society. Participants included international experts from pulmonary medicine, occupational medicine, radiology, pathology, and exposure science. The meeting objectives were to 1) define currently available tools for exposure assessment in evaluation of HP, 2) describe the evidence base supporting the role for these exposure assessment tools in HP evaluation, 3) identify limitations and barriers to each tool's implementation in clinical practice, 4) determine which exposure assessment tools demonstrate the best performance characteristics and applicability, and 5) identify research needs for improving exposure assessment tools for HP. Specific discussion topics included history-taking and exposure questionnaires, antigen avoidance, environmental assessment, specific inhalational challenge, serum-specific IgG testing, skin testing, lymphocyte proliferation testing, and a multidisciplinary team approach. Priorities for research in this area were identified.

Assessment and Management of Occupational Hypersensitivity Pneumonitis

The diagnosis and treatment of occupational hypersensitivity pneumonitis (OHP) remain complex and challenging in the absence of diagnostic gold standards or clinical guidelines. This review provides an update of the recent literature regarding the different presentations of OHP and the diagnostic yield and value of the diagnostic tests currently available, which include occupational and medical history, laboratory tests (serum-specific immunoglobulins, environmental sampling), imaging, bronchoalveolar lavage, transbronchial biopsy, transbronchial cryobiopsy, surgical lung biopsy, and specific inhalation challenges. These tools provide a precise differential diagnosis within the framework of interstitial lung diseases. However, among the chronic fibrotic forms, distinguishing OHP from sarcoidosis, nonspecific interstitial pneumonia and idiopathic pulmonary fibrosis remains a diagnostic challenge. Avoidance of exposure is pivotal for OHP management, whereas corticosteroids are fundamental in the pharmacological approach to this disease. In addition, studies describing the long-term benefits of immunosuppressive and antifibrotic agents have increased the use of these treatments in OHP.

Hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a complex syndrome caused by the inhalation of a variety of antigens in susceptible and sensitized individuals. These antigens are found in the environment, mostly derived from bird proteins and fungi. The prevalence and incidence of HP vary widely depending on the intensity of exposure, the geographical area and the local climate. Immunopathologically, HP is characterized by an exaggerated humoral and cellular immune response affecting the small airways and lung parenchyma. A complex interplay of genetic, host and environmental factors underlies the development and progression of HP. HP can be classified into acute, chronic non-fibrotic and chronic fibrotic forms. Acute HP results from intermittent, high-level exposure to the inducing antigen, usually within a few hours of exposure, whereas chronic HP mostly originates from long-term, low-level exposure (usually to birds or moulds in the home), is not easy to define in terms of time, and may occur within weeks, months or even years of exposure. Some patients with fibrotic HP may evolve to a progressive phenotype, even with complete exposure avoidance. Diagnosis is based on an accurate exposure history, clinical presentation, characteristic high-resolution CT findings, specific IgG antibodies to the offending antigen, bronchoalveolar lavage and pathological features. Complete antigen avoidance is the mainstay of treatment. The pharmacotherapy of chronic HP consists of immunosuppressive drugs such as corticosteroids, with antifibrotic therapy being a potential therapy for patients with progressive disease.

Incidence, comorbidity and survival rate of hypersensitivity pneumonitis: a national population-based study

Background and objectives

Hypersensitivity pneumonitis (HP) is a rare disease, which can lead to premature death. Few studies have investigated HP on a national level. The objective of this study was to investigate incidence, survival rate, and comorbidity of HP in Denmark.

Methods

Using the Danish National Patient Registry we identified all patients with a first-time diagnosis of HP between 1998 and 2010. Patients with HP were matched 1:4 with controls by sex, age and geography in this case-control study. Comorbidity 3 years prior to diagnosis was explored by the Charlson score index. Survival rates were assessed using Kaplan–Meier curves and hazard ratios.

Results

We identified 753 patients during the observation period equalling an average HP incidence of 1.16 per 100 000 citizens. Patients with HP had a significantly higher Charlson score index when compared with the matched controls and an increased risk of dying (hazard ratio 1.98, CI 1.61–2.58, se 0.14, p<0.001). Survival rates of HP were lower at all time points when compared with the matched control population. The decline in survival was observed for both male and female patients with HP with no clear sex difference. Most deaths were related to diseases of the heart and lungs.

Conclusions

In this Danish longitudinal nationwide observational study we found an increased Charlson score index combined with a higher mortality without sex difference among patients with HP compared with a healthy control group, mainly due to diseases of the heart and lungs.

Hypersensitivity pneumonitis is rare and associated with increased mortality rates especially during the first 2 years following diagnosishttp://bit.ly/2oo7tiR

Epidemiology of Hypersensitivity Pneumonitis among an Insured Population in the United States: A Claims-based Cohort Analysis

RATIONALE

Hypersensitivity pneumonitis is a complex lung disease resulting from repeated inhalation of a variety of antigens. Limited data exist regarding its epidemiology.

OBJECTIVES

To describe the trends in the annual incidence and prevalence of hypersensitivity pneumonitis in the United States.

METHODS

We developed novel claims-based coding algorithms to identify hypersensitivity pneumonitis, chronic hypersensitivity pneumonitis, and fibrotic hypersensitivity pneumonitis cases using the 2004 to 2013 MarketScan Commercial and Medicare Supplemental healthcare claims databases. Algorithm validity and reliability were assessed with clinical data from National Jewish Health. We calculated yearly cumulative incidence and prevalence overall and by age. For the subgroup with vital status, Kaplan-Meier methods were used to analyze survival stratified by evidence of fibrosis.

RESULTS

We identified 7,498 cases that met our hypersensitivity pneumonitis definition over the 10-year study period, including 3,902 with chronic hypersensitivity pneumonitis and 1,852 with fibrotic hypersensitivity pneumonitis. On the basis of the clinical-radiological adjudication of the validation sample, 38 cases (95%) were confirmed as hypersensitivity pneumonitis. The mean age was 52 years, and 58% were women. The 1-year prevalence rates for hypersensitivity pneumonitis ranged from 1.67 to 2.71 per 100,000 persons, and 1-year cumulative incidence rates ranged from 1.28 to 1.94 per 100,000 persons. The prevalence increased with age, ranging from 0.95 per 100,000 among 0- to 9-year-olds to 11.2 per 100,000 among those aged 65 years and older. Between 56 and 68% of hypersensitivity pneumonitis cases in each year were classified as chronic hypersensitivity pneumonitis (prevalence, 0.91-1.70 per 100,000 persons; cumulative incidence, 0.63-1.08 per 100,000 persons). Fewer had fibrotic hypersensitivity pneumonitis (prevalence, 0.41-0.80 per 100,000 persons; cumulative incidence: 0.29-0.43 per 100,000 persons). Most cases (74%) were classified as unspecified hypersensitivity pneumonitis. Older age, male sex, and fibrosis were associated with higher mortality rates in unadjusted analyses.

CONCLUSIONS

Using U.S. administrative claims-based data, we developed an algorithm with a high sensitivity and specificity for hypersensitivity pneumonitis. Between 2004 and 2013, hypersensitivity pneumonitis was more common among women and those older than 65 years. Most cases were classified as chronic hypersensitivity pneumonitis. Approximately one-fourth met our criteria for fibrotic hypersensitivity pneumonitis, which was associated with a higher mortality rate.

Presence of Air Trapping and Mosaic Attenuation on Chest Computed Tomography Predicts Survival in Chronic Hypersensitivity Pneumonitis

RATIONALE

Significant heterogeneity of computed tomography (CT) presentation exists within chronic hypersensitivity pneumonitis (HP). There are limited data aimed at delineating the prognostic value of specific CT features, distribution, and patterns in chronic HP.

OBJECTIVES

To examine whether the presence of CT mosaic attenuation (MA) and air trapping (AT), and the distribution or patterns of fibrosis impact survival in subjects with chronic HP.

METHODS

We retrospectively identified 110 consecutively enrolled, well-characterized, biopsy-proven adult subjects with chronic HP between 1982 and 2015 from the National Jewish Health interstitial lung disease research database. The first available CT scan of diagnostic quality from each subject was formally evaluated for specific CT findings associated with chronic HP and for overall CT pattern. A Cox proportional hazards model was used to identify independent predictors in time-to-death analysis, and bootstrap analysis was performed for internal model validation.

RESULTS

Fibrotic HP (65%; 72/110) was most often peripheral in the axial plane and lower lung preponderant. The distribution of lung disease in those without fibrosis was most often axially and zonally diffuse. There was no association between survival and CT distribution or CT pattern in the whole cohort or within the fibrotic subset of subjects. After multivariate adjustment, AT/MA was independently associated with survival in the whole cohort (HR = 0.26; 95% confidence interval = 0.07-0.97). Results were similar after restricting the analyses to fibrotic HP cases.

CONCLUSIONS

Among subjects with chronic HP, the presence of CT AT/MA may identify subjects with better prognosis.

Hypersensitivity pneumonitis: a complex lung disease

Hypersensitivity pneumonitis (HP), also called extrinsic allergic alveolitis, is a respiratory syndrome involving the lung parenchyma and specifically the alveoli, terminal bronchioli, and alveolar interstitium, due to a delayed allergic reaction. Such reaction is secondary to a repeated and prolonged inhalation of different types of organic dusts or other substances to which the patient is sensitized and hyper responsive, primarily consisting of organic dusts of animal or vegetable origin, more rarely from chemicals. The prevalence of HP is difficult to evaluate because of uncertainties in detection and misdiagnosis and lacking of widely accepted diagnostic criteria, and varies considerably depending on disease definition, diagnostic methods, exposure modalities, geographical conditions, agricultural and industrial practices, and host risk factors. HP can be caused by multiple agents that are present in work places and in the home, such as microbes, animal and plant proteins, organic and inorganic chemicals. The number of environment, settings and causative agents is increasing over time. From the clinical point of view HP can be divided in acute/subacute and chronic, depending on the intensity and frequency of exposure to causative antigens. The mainstay in managing HP is the avoidance of the causative antigen, though the complete removal is not always possible due to the difficulties to identify the agent or because its avoidance may lead to major changes in life style or occupational settings. HP is a complex syndrome that needs urgently for more stringent and selective diagnostic criteria and validation, including wider panels of IgG, and a closer collaboration with occupational physicians, as part of a multidisciplinary expertise.

Occupational hypersensitivity pneumonitis: an EAACI position paper

The aim of this document was to provide a critical review of the current knowledge on hypersensitivity pneumonitis caused by the occupational environment and to propose practical guidance for the diagnosis and management of this condition. Occupational hypersensitivity pneumonitis (OHP) is an immunologic lung disease resulting from lymphocytic and frequently granulomatous inflammation of the peripheral airways, alveoli, and surrounding interstitial tissue which develops as the result of a non-IgE-mediated allergic reaction to a variety of organic materials or low molecular weight agents that are present in the workplace. The offending agents can be classified into six broad categories that include bacteria, fungi, animal proteins, plant proteins, low molecular weight chemicals, and metals. The diagnosis of OHP requires a multidisciplinary approach and relies on a combination of diagnostic tests to ascertain the work relatedness of the disease. Both the clinical and the occupational history are keys to the diagnosis and often will lead to the initial suspicion. Diagnostic criteria adapted to OHP are proposed. The cornerstone of treatment is early removal from exposure to the eliciting antigen, although the disease may show an adverse outcome even after avoidance of exposure to the causal agent.

The amount of avian antigen in household dust predicts the prognosis of chronic bird-related hypersensitivity pneumonitis

RATIONALE

Bird-related hypersensitivity pneumonitis is induced by inhalation of avian antigen. Evaluation to avoid repeated exposure to avian antigen is a key part of the treatment for bird-related hypersensitivity pneumonitis. It can be difficult, however, to reliably evaluate exposure to the antigen because bird-related hypersensitivity pneumonitis in its chronic form may be caused by unrecognized and indirect exposure.

OBJECTIVE

The purpose of the present study is to establish a method for measuring environmental avian antigen in patients with chronic bird-related hypersensitivity pneumonitis and to evaluate the clinical utility of the method.

METHODS

The amount of avian antigen was measured in samples of dust collected from the household environments of patients with chronic bird-related hypersensitivity pneumonitis. The patients whose clinical progress could be followed by periodic pulmonary function tests for 1 year were classified into a deterioration group and a stable group. Age, sex, smoking status, FVC % predicted, and the amount of avian antigen in household dust samples at the diagnosis of bird-related hypersensitivity pneumonitis, as well as survival, were determined and evaluated for each group. The total number of subjects was 23.

MEASUREMENTS AND MAIN RESULTS

The clinical condition deteriorated in 11 patients and remained stable in 12. The amount of avian antigen in household dust samples was significantly higher for the deterioration group than for the stable group. In logistic regression analysis, avian antigen was the only variable found to be significant for distinguishing between the two groups. The patients with higher amounts household dust avian antigen had a poor prognosis in the survival analysis. Avian antigen was the only variable to significantly influence the prognosis of chronic bird-related hypersensitivity pneumonitis.

CONCLUSIONS

The levels of exposure to avian antigen were related to disease progression and prognosis in chronic bird-related hypersensitivity pneumonitis.

Radiographic fibrosis score predicts survival in hypersensitivity pneumonitis

BACKGROUND

It is unknown if the radiographic fibrosis score predicts mortality in persistent hypersensitivity pneumonitis (HP) and if survival is similar to that observed in idiopathic pulmonary fibrosis (IPF) when adjusting for the extent of radiographic fibrosis.

METHODS

We reviewed records from 177 patients with HP and 224 patients with IPF whose diagnoses were established by multidisciplinary consensus. Two thoracic radiologists scored high-resolution CT (HRCT) scan lung images. Independent predictors of transplant-free survival were determined using a Cox proportional hazards analysis. Kaplan-Meier survival curves were constructed, stratified by disease as well as fibrosis score.

RESULTS

HRCT scan fibrosis score and radiographic reticulation independently predicted time to death or lung transplantation. Clinical predictors included a history of cigarette smoking, auscultatory crackles on lung examination, baseline FVC, and FEV1/FVC ratio. The majority of HP deaths occurred in patients with both radiographic reticulation and auscultatory crackles on examination, compared with patients with only one of these manifestations (P &lt; .0001). Patients with IPF had worse survival than those with HP at any given degree of radiographic fibrosis (hazard ratio 2.31; P &lt; .01).

CONCLUSIONS

Survival in patients with HP was superior to that of those with IPF with similar degrees of radiographic fibrosis. The combination of auscultatory crackles and radiographic reticulation identified patients with HP who had a particularly poor outcome.

Chronic hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a complex syndrome caused by the inhalation of environmental antigens. Chronic HP may mimic other fibrotic lung diseases, such as idiopathic pulmonary fibrosis. Recognition of the antigen is important for diagnosis; avoidance of further exposure is critical for treatment. Fibrosis on biopsy or high-resolution computed tomography is a predictor of increased mortality. Additional research is needed to understand why the disease develops only in a minority of exposed individuals and why cases of chronic HP may progress without further antigen exposure.

High-resolution CT findings of parenchymal fibrosis correlate with prognosis in hypersensitivity pneumonitis

BACKGROUND

Histopathologic evidence of fibrosis on surgical lung biopsy has been associated with reduced survival in patients with hypersensitivity pneumonitis (HP). Changes of pulmonary fibrosis detected on CT may also correlate with prognosis in patients with HP.

METHODS

We identified 69 consecutive patients with HP diagnosed between January 1997 and December 2002 at Mayo Clinic, Rochester, MN. Patients were stratified into fibrotic and nonfibrotic groups based on the CT findings. Fibrosis was defined by the presence of irregular linear opacities, traction bronchiectasis, or honeycombing.

MEASUREMENTS AND MAIN RESULTS

Of 69 patients, 26 were classified as fibrotic and 43 as nonfibrotic. Patients in the fibrotic group were older, had longer symptom duration, were more likely to have crackles on auscultation, more likely to be exposed to avian antigen, and had greater restrictive lung impairment (p<0.05 for all comparisons). There were 11 deaths in the fibrotic group and 1 death in the nonfibrotic group (p<0.0001). In the regression analysis, CT evidence of fibrosis, more severe pulmonary function abnormalities, and the presence of crackles on auscultation were predictive of reduced survival (p<0.05 for all). The presence as well as the extent of fibrosis on CT was associated with increased mortality. The age-adjusted hazard ratio for mortality in patients with fibrosis was 4.6 (95% confidence interval, 2.0 to 20.1; p<0.0001).

CONCLUSION

CT findings of parenchymal fibrosis are associated with reduced survival in patients with HP and may serve as a useful prognostic indicator.

Bird fancier's lung: a series of 86 patients

Bird fancier's lung (BFL) is one of the most common types of hypersensitivity pneumonitis. Nevertheless, the criteria for diagnosing this condition are not standardized. The current study is an in-depth investigation into the clinical characteristics of BFL in the largest series examined for this purpose by a single group, to our knowledge, taking into account the acute, subacute, or chronic clinical presentation. From 1977 to 2003, BFL was diagnosed in 86 patients using a homogeneous protocol. Data from the clinical history and physical examination were analyzed, as well as the results from the following complementary examinations: laboratory analyses, specific serum IgG antibodies determination, chest X-ray, chest computed tomography (CT), pulmonary function testing, immediate hypersensitivity skin testing, delayed cutaneous hypersensitivity testing, bronchofibroscopy with bronchoalveolar lavage (BAL) and/or transbronchial biopsy, bronchial challenge testing, and surgical lung biopsy. In addition, clinical and epidemiologic characteristics were determined in a control group of 60 pigeon breeders who did not meet the diagnostic criteria of BFL. Eighty-six patients (21 men and 65 women) with a mean age of 47 years were studied. Seven (8%) patients were younger than 15 years of age at the time of the diagnosis. In 3 cases, the disease was caused by exposure to feather-filled bedding. Nearly 1 in 5 patients was diagnosed in the chronic phase of the disease. The mean diagnostic delay was 1.6 years overall, and 3.2 years in patients diagnosed in the chronic phase of the disease. Among the 17% of patients with chronic disease, the mean interval from initiation of exposure to diagnosis was 16 years, a higher value than in the acute or subacute presentation forms. Dyspnea and cough were the most common clinical symptoms (98% and 82%, respectively), and nearly 25% had grade III or IV dyspnea at diagnosis. Only 18% of patients experienced chest tightness, a symptom classically considered to be frequent in this condition. Erythrocyte sedimentation rate was elevated (>30 mm/h) in 44% of patients. Urinary calcium was elevated in 20% of patients. Angiotensin-converting enzyme was not elevated in any of the patients in which it was measured. Lactate dehydrogenase increases were found in 51% of patients. Specific IgG antibodies to avian antigens were documented in 92% of BFL patients, but also in 87% of pigeon breeder controls. The most frequent radiologic finding was an interstitial pattern in 79% of patients. Common chest CT features were ground glass areas (68%) and a mosaic pattern (61%); areas of emphysema were found in 7/41 (17%) patients, 5 of whom had never smoked. Two patients had a CT pattern of pulmonary fibrosis indistinguishable from idiopathic pulmonary fibrosis. Immediate hypersensitivity skin testing with bird sera and pigeon bloom was positive in 78% and 100% of BFL patients, respectively, and in 64% and 88% of control pigeon breeders, respectively. Almost one-third of the patients (29%) presented an anergic response on delayed cutaneous hypersensitivity testing. Restrictive ventilatory impairment was the most frequent functional pattern (77%), although 9% and 4% showed a pure obstructive and mixed pattern, respectively. The carbon monoxide diffusing capacity was decreased (<80% of the predicted value) in 85% of cases. Forty-one percent of patients had PaO2 <60 mm Hg at diagnosis when blood gas analysis was performed. Lymphocytosis (>20% lymphocytes) was documented in 83% of patients who underwent BAL, with a similar frequency in the 3 presentation forms: 70% acute, 89% subacute, and 85% chronic. In addition, inversion of the CD4/CD8 ratio (<1) was observed in 62% of the patients, but 38% of cases showed a CD4 predominance. The characteristic triad of histopathologic findings in hypersensitivity pneumonitis was found in only 9% of patients undergoing transbronchial biopsy, but at least 1 of these findings was seen in 69%. Surgical lung biopsy was undertaken in 14/86 (16%) patients; the complete triad was observed in 50% and at least 1 finding in 100%. In 54/86 (63%) patients, the diagnosis was confirmed by bronchial challenge testing, a test with a sensitivity of 92% and specificity of 100%. BFL is a potentially severe disease that can progress to respiratory failure secondary to pulmonary fibrosis or chronic obstructive pulmonary disease, as a form of chronic occupational respiratory disease. Respiratory symptoms in exposed patients, including children and adults who have only 1 pet bird at home, should raise the suspicion of BFL. Diagnosis in the chronic phase is frequent, and the delay to diagnosis was greatest in these cases. Elevated urinary calcium, lactate dehydrogenase, and erythrocyte sedimentation rate in a bird fancier may constitute a combined marker for suspected BFL. Chest CT frequently discloses emphysema and a pattern of idiopathic pulmonary fibrosis in some patients. An anergic response on delayed cutaneous hypersensitivity testing is not infrequent. The presentation with respiratory failure and the predominance of CD4 T lymphocytes in some patients' BAL are both remarkable. Lymphocytosis on BAL also persists in the chronic phase of the disease. Bronchial challenge testing has a high diagnostic yield, and surgical lung biopsy is not needed to reach the final diagnosis in the vast majority of cases.

Les pneumopathies d’hypersensibilité en milieu professionnel

INTRODUCTION

Hypersensitivity pneumonitis (HP) is a granulomatous disease of the lungs due to immune reactions following chronic inhalation of organic dusts or chemicals especially encountered in the occupational environment. The main purpose of this review is to report current concepts regarding aetiologies, epidemiology, diagnosis, treatment as well as legal aspects of HP.

STATE OF THE ART

The following aspects will be focused: (1) increase in new etiological circumstances, especially occupational and news antigens, (2) for diagnosis, the major contribution of chest high resolution CT scan which often shows characteristic images but also recent developments in simple diagnostic criteria that may be used for an epidemiological approach, (3) importance of bronchial obstruction and even emphysema as a long term sequelae, finally (4) the possibility of continuing occupational activities in certain circumstances where preventive measures can be used.

PERSPECTIVES

The increasing knowledge of etiological agents and circumstances as well as the development of secondary and especially primary preventive measures should lead to reduce the frequency of this disease and of its medico-social consequences.

The effect of pulmonary fibrosis on survival in patients with hypersensitivity pneumonitis

PURPOSE

To determine the effect of pulmonary fibrosis on survival in an unselected group of patients with hypersensitivity pneumonitis.

METHODS

We identified 72 patients with hypersensitivity pneumonitis confirmed by surgical lung biopsy in the database of the Clinical Interstitial Lung Disease Program at the National Jewish Medical and Research Center. All biopsy specimens were scored according to the presence or absence of fibrosis. Comparisons were made between patients with (fibrotic group) and without (nonfibrotic group) pathologic fibrosis. Vital status was ascertained and Kaplan-Meier curves were plotted. Cox regression analysis was used to determine predictors of survival.

RESULTS

Forty-six patients were classified as fibrotic and 26 as nonfibrotic. Twenty-nine percent had exposure to a bird antigen, 33% had exposure to a microbial antigen, and 38% had unknown exposure. Patients with fibrosis were significantly older, showed greater restrictive lung physiology, and had greater all-cause and respiratory mortality. Median survival in fibrotic patients was 7.1 years, which was significantly less than survival in those without fibrosis. In an age-adjusted regression analysis, antigen class, symptom duration, and lung function had no effect on survival. Only the presence of pathologic fibrosis was predictive of increased mortality (hazard ratio = 6.01; 95% confidence interval: 1.68 to 21.45; P = 0.006).

CONCLUSION

Pulmonary fibrosis is associated with diminished survival in patients with hypersensitivity pneumonitis.

Suberosis: clinical study and new etiologic agents in a series of eight patients

BACKGROUND

Penicillium frequentans is considered to be the causal agent of suberosis, hypersensitivity pneumonitis due to cork dust inhalation. Nevertheless, other fungi can colonize cork during its storage period in humid conditions. The aims of the study were to assess the etiologic role of several fungi and cork itself in the genesis of suberosis, and to review the clinical characteristics of patients with this disease.

METHODS

Eight patients with suberosis were studied. Chest radiography, high-resolution chest CT, pulmonary function testing, bronchofibroscopy with BAL and transbronchial biopsy, and delayed cutaneous hypersensitivity tests were performed. Fungal and suberin (cork that is culture negative for fungi) antigens were used for serum determination of specific IgG antibodies, immediate hypersensitivity specific skin tests, and specific bronchial challenge tests.

RESULTS

Serum specific IgG antibody determinations and specific skin tests against Aspergillus fumigatus and suberin demonstrated the capacity of both these antigenic extracts to induce an immunologic response. Positive specific bronchial challenge tests performed not only with P frequentans but also with A fumigatus, and cork itself were recorded in some patients for the first time in this disease. Dyspnea and cough were the most frequent symptoms. Clinical and functional improvement occurred after antigen avoidance.

CONCLUSIONS

In addition to P frequentans, A fumigatus and cork dust itself may contribute to the development of suberosis.

Clinical and radiologic manifestations of hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is an inflammatory interstitial lung disease caused by recurring exposure to a variety of occupational and environmental antigens. It features widely variable clinical, radiologic, and histopathologic findings. Because the clinical findings of HP mimic multiple other diseases, a high degree of clinical suspicion and a thorough occupational and environmental history are essential for accurate diagnosis. There is no single pathognomonic feature for HP; rather, diagnosis relies on a constellation of clinical, radiologic, and pathologic findings. The radiologic manifestations, particularly the high-resolution computed tomography (HRCT) pattern, provide important clues and frequently point clinicians towards the correct diagnosis. The HRCT findings in HP may include ground-glass opacification, centrilobular nodules, air trapping (mosaic pattern), fibrosis, emphysema, or more frequently a combination of these. The combination of a mosaic pattern with ground-glass opacification and centrilobular nodules is particularly suggestive of the diagnosis. The best long-term prognosis is achieved with early diagnosis and removal from exposure.

Follow up investigation of workers in synthetic fibre plants with humidifier disease and work related asthma

OBJECTIVE

To investigate the clinical and sociomedical outcome in patients with various clinical manifestations of humidifier disease and work related asthma after removal from further exposure.

METHODS

Follow up investigation (range 1-13 years) of respiratory symptoms, spirometry, airway responsiveness, sickness absence, and working situation in patients with (I) humidifier fever (n = 12), (II) obstructive type of humidifier lung (n = 8), (III) restrictive type of humidifier lung (n = 4), and (IV) work related asthma (n = 22). All patients were working at departments in synthetic fibre plants with microbiological exposure from contaminated humidification systems or exposure to small particles (< 1 micron) of oil mist.

RESULTS

At follow up patients with work related asthma were less often symptom free (37%, 7/19) than patients with humidifier disease (I, II, III) (67%, 16/24). Mean forced expiratory volume in one second (FEV1) of patients with obstructive impairment had been increased significantly at follow up but still remained below the predicted value. Mean forced vital capacity (FVC) of patients with initially restrictive impairment had returned to normal values at follow up. Airway hyperresponsiveness at diagnosis persisted in patients with obstructive impairment (II + IV 14/17, but disappeared in patients with humidifier fever (3/3) and restrictive type of humidifier lung (2/2). In patients with obstructive impairment (II + IV), FVC and FEV1 at diagnosis were negatively associated with the duration between onset of symptoms and diagnosis and the number of years of exposure. Those with positive pre-employment history of respiratory disease had a lower FEV1 at diagnosis. Sickness absence due to respiratory symptoms decreased in all groups of patients after removal from further exposure, but this was most impressive in patients with the humidifier lung (II, III) and patients with work related asthma (IV). At follow up 83% of the patients were still at work at the same production site, whereas 11% received a disability pension because of respiratory disease.

CONCLUSION

In patients with work related respiratory disease caused by exposure from contaminated humidification systems or oil mist, removal from further exposure resulted in clinical improvement, although, especially in those with obstructive impairment, signs persisted. Because of the possibility of transferring patients to exposure-free departments most patients could be kept at work.

[Subacute extrinsic allergic alveolitis with lesion edema]

BACKGROUND

Extrinsic allergic alveolitis may have a chronic, subacute or acute course. Its fulminant form with interstitial edema is unusual.

CASE REPORT

An 11-year-old girl was referred to our intensive care unit because she suffered from high fever. Chest X-rays showed bilateral alveolitis. History revealed home exposure to several birds for many years, and episodes of dyspnea and fever for a few months. Diagnosis of extrinsic allergic alveolitis was confirmed by strongly positive results of precipitins to avian antigens. In addition, a paramyxovirus influenzae was recovered from broncho-alveolar lavage. Treatment, including high dose steroids, hydroxychloroquine, and suppression of antigenic exposure allowed weaning from mechanical ventilation after 50 days. Severe pulmonary restriction was disclosed by lung function testing following weaning and slow improvement occurred 5 months later, despite persistent interstitial lesions on chest X-rays.

CONCLUSION

Extrinsic allergic alveolitis may mimic an acute respiratory distress syndrome. Documenting bird exposure in such a case helps to achieve appropriate diagnosis which requires early administration of steroids in order to improve vital and functional prognosis.

Pigeon-breeder's lung. Extensive workup clarifies the clinical picture

Pigeon-breeder's lung should be included in the differential diagnosis when patients present with interstitial lung disease or intermittent cough and dyspnea. No single test confirms the diagnosis. Rather, careful attention must be given to results of history taking, physical examination, pulmonary function and precipitin testing, chest radiography, and, if indicated, lung biopsy. Symptoms usually resolve when exposure to suspected antigens is avoided.