The hypersensitivity pneumonitis diagnostic index: use of non-invasive testing to diagnose hypersensitivity pneumonitis in metalworkers

Hypersensitivity pneumonitis in workers exposed to metalworking fluids

Background

This study used data from a large UK outbreak investigation, to develop and validate a new case definition for hypersensitivity pneumonitis due to metalworking fluid exposure (MWF-HP).

Methods

The clinical data from all workers with suspected MWF-HP were reviewed by an experienced panel of clinicians. A new MWF-HP Score was then developed to match the “gold standard” clinical opinion as closely as possible, using standard diagnostic criteria that were relatively weighted by their positive predictive value.

Results

The new case definition was reproducible, and agreed with expert panel opinion in 30/37 cases. This level of agreement was greater than with any of the three previously utilized case definitions (agreement in 16–24 cases). Where it was possible to calculate, the MWF-HP Score also performed well when applied to 50 unrelated MWF-HP cases.

Conclusions

The MWF-HP Score offers a new case definition for use in future outbreaks. Am. J. Ind. Med. 57:872–880, 2014. © 2014 The Authors. American Journal of Industrial Medicine Published by Wiley Periodicals, Inc.

Systematic review of respiratory case definitions in metalworking fluid outbreaks

BACKGROUND

Since the mid-1990s, outbreaks of asthma and extrinsic allergic alveolitis (EAA) have been identified in workers exposed to metalworking fluids (MWFs). The cause of these outbreaks remains to be determined.

AIMS

To identify and review all previously published occupational lung disease case definitions and diagnostic criteria that have been utilized during MWF outbreak investigations.

METHODS

Respiratory outbreaks due to MWFs were identified by a systematic literature search for articles published between 1990 and October 2011. Investigations reporting the usage of disease case definitions or diagnostic criteria for respiratory disease were reviewed and summarized.

RESULTS

The literature search identified 35 papers relating to 27 outbreaks of respiratory disease in MWF-exposed workers. Fourteen case definitions for MWF-related respiratory disease were identified: seven for EAA, five for occupational asthma and one each for humidifier fever and industrial bronchitis. A single paper was identified where any comparison of different disease case definitions (for EAA) had been performed.

CONCLUSIONS

A range of case definitions and diagnostic criteria for MWF respiratory disease have been utilized in outbreak investigations, but the majority have been produced for individual outbreak investigations without previous validation. It may be difficult to compare the findings of future workplace studies without a more standardized approach to case identification and diagnosis.

Systematic review of respiratory outbreaks associated with exposure to water-based metalworking fluids

INTRODUCTION

Potential demographic risk factors for outbreaks of respiratory disease due to water-based metalworking fluids (MWFs) were investigated through systematic review of published outbreak investigations.

METHODS

Search terms were selected by a multidisciplinary team, assisted by an experienced library information service. Several computerized literature databases were searched for articles published between January 1990 and October 2011, relating to ill health outbreaks due to MWFs. Papers meeting the search criteria were reviewed in detail, and their references checked for additional articles. Study design and demographic details of the outbreak were extracted from the selected articles and entered into standardized evidence tables.

RESULTS

Thirty-five articles relating to investigations of 27 outbreaks of respiratory ill health attributed to MWF exposure were identified. The majority of reports were case series of disease or observational cross-sectional studies of symptoms and hygiene measurements. Eight of the outbreak investigations included an element of case-control analysis. Most outbreaks were from the USA, had occurred in large car- or aeronautical-manufacturing plants, and were associated with the use of central shared sumps. Hygiene studies have not demonstrated consistent risk factors for respiratory outbreaks, in terms of the type of MWF utilized, degree of microbial contamination, or levels of personal exposure. Six studies were identified that found workers with MWF exposure during outbreaks were more likely to report respiratory or systemic symptoms than unexposed control workers. Six case-control analyses were also identified that found workers with extrinsic allergic alveolitis (EAA) were more likely to demonstrate certain immune responses to microbial contaminants and/or used MWFs than workers without EAA.

CONCLUSION

Despite a number of detailed workplace and immunological studies of asthma and alveolitis outbreaks in MWF-exposed workforces, our understanding of their aetiology remains limited.

New evidence on the health hazards and control of metalworking fluids since completion of the OSHA advisory committee report

BACKGROUND

Metalworking fluids (MWF) are used in the manufacture of engines, transmissions, chassis parts and other products. In 2003, OSHA denied a union petition to promulgate a standard for MWF. The 3rd Circuit Court of Appeals rejected a union lawsuit to compel OSHA to regulate MWF. OSHA relied exclusively on the 1999 Metal Working Fluids Standards Advisory Committee report, therefore, only evidence available before 1999 was quoted supporting the denial. This review was conducted to identify studies published since 1998.

METHODS

Electronic reference sources were queried for the terms for metalworking fluids, machining fluids, cutting fluids, cutting oils, coolants, machining, and machinist. All items returned were reviewed for relevance to MWF regulation.

RESULTS

The review noted 227 reports in the peer reviewed literature directly relevant to regulation of MWF exposures. Of these, 26 addressed cancer; 58 respiratory effects; 32 skin effects or absorption; 45 microbial contaminants; and 76 exposure measurements and controls. Three major studies identified excess cancer including lung, liver, pancreatic, laryngeal, and leukemia associated with MWF exposures. Reports strengthened associations of asthma and hypersensitivity pneumonitis with recent exposure to MWF.

CONCLUSIONS

Material new evidence demonstrates significant risks to material impairment of health at prevailing exposure levels and feasibility of lower exposure limits.

Hypersensitivity pneumonitis

The first few cases of hypersensitivity pneumonitis (HP) were described in the early 20th century in farmers exposed to moldy hay or straw. As then, HP has been ascribed to multiple inhaled antigens found in a large variety of environmental settings. Hypersensitivity pneumonitis results from an exaggerated immune response, which gives rise to acute infection-like symptoms or to progressive, sometimes irreversible lung damage. The diagnosis is based on a combination of clinical characteristics of the disease. Clinical diagnostic criteria have recently been published. The immune mechanisms leading to HP are still incompletely understood. Initially, believed to be a classes III and IV immune response, we now have a clearer understanding of the complex inflammatory events involved. These include the release of pro inflammatory cytokines and a decrease in the immune control mechanisms via surfactant, dendritic and T-regulatory cells. Despite the improved understanding, the treatment and outcome of HP have not changed. Oral corticosteroids remain the only effective drugs and contact withdrawal constitutes the ideal solution. If unchecked, HP can lead to irreversible lung damage in the form of fibrosis or emphysema, respiratory insufficiency and even death.

[Granulomatous diseases of occupational etiology]

A variety of diseases are encompassed in the didactic denomination of "granulomatous diseases of probable occupational etiology". As well as presenting similar clinical aspects, such diseases are characterized by certain common traits: formation of granulomas; systemic and respiratory manifestations; environmental or occupational exposure to organic or inorganic agents; and T lymphocyte involvement in the pathogenesis. Included in this category are hypersensitivity pneumonitis, mycobacteriosis (all forms) and sarcoidosis, as well as beryllium disease and other lung diseases caused by exposure to heavy metals. In order to highlight the risk of developing one of these diseases as a result of environmental or occupational exposure to etiologic agents, we address aspects related to epidemiology, pathogenesis and evaluation of exposure of these diseases, as well as those related to diagnostic criteria, prevention and control. We have given special emphasis to groups of individuals considered to be at high risk for developing these diseases, as well as to the need for health care professionals to remain aware of the potential occupational etiology of such diseases, a decisive factor in devising effective measures of prevention and epidemiological surveillance.

Hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a pulmonary disease with symptoms of dyspnea and cough resulting from the inhalation of an antigen to which the subject has been previously sensitized. The incidence of HP is unknown. A population-based study estimated the annual incidence of interstitial lung diseases as 30:100,000 and HP accounted for less than 2% of these cases. The diagnosis of HP can often be made or rejected with confidence, especially in areas of high or low prevalence respectively, using simple diagnostic criteria. Chest X-rays may be normal in active HP; High Resolution Computed Tomography is sensitive but not specific for the diagnosis of HP. The primary use of pulmonary function tests is to determine the physiologic abnormalities and the associated impairment. Despite the pitfalls of false positive and false negatives, antigen-specific IgG antibodies analysis can be useful as supportive evidence for HP. Bronchoalveolar lavage plays an important role in the investigation of patients suspected of having HP. A normal number of lymphocytes rules out all but residual disease. Surgical lung biopsy should be reserved for rare cases with puzzling clinical presentation or for verification the clinical diagnosis when the clinical course or response to therapy is unusual. Being an immune reaction in the lung, the most obvious treatment of HP is avoidance of contact with the offending antigen. Systemic corticosteroids represent the only reliable pharmacologic treatment of HP but do not alter the long-term outcome. The use of inhaled steroids is anecdotal. Treatment of chronic or residual disease is supportive.

Quantifying serum antibody in bird fanciers' hypersensitivity pneumonitis

Background

Detecting serum antibody against inhaled antigens is an important diagnostic adjunct for hypersensitivity pneumonitis (HP). We sought to validate a quantitative fluorimetric assay testing serum from bird fanciers.

Methods

Antibody activity was assessed in bird fanciers and control subjects using various avian antigens and serological methods, and the titer was compared with symptoms of HP.

Results

IgG antibody against pigeon serum antigens, quantified by fluorimetry, provided a good discriminator of disease. Levels below 10 mg/L were insignificant, and increasing titers were associated with disease. The assay was unaffected by total IgG, autoantibodies and antibody to dietary hen's egg antigens. Antigens from pigeon serum seem sufficient to recognize immune sensitivity to most common pet avian species. Decreasing antibody titers confirmed antigen avoidance.

Conclusion

Increasing antibody titer reflected the likelihood of HP, and decreasing titers confirmed antigen avoidance. Quantifying antibody was rapid and the increased sensitivity will improve the rate of false-negative reporting and obviate the need for invasive diagnostic procedures. Automated fluorimetry provides a method for the international standardization of HP serology thereby improving quality control and improving its suitability as a diagnostic adjunct.

Needs and Opportunities for Research in Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis (HP) develops after inhalation of many different environmental antigens, causing variable clinical symptoms that often make diagnosis uncertain. The prevalence of HP is higher than recognized, especially its chronic form. Mechanisms of disease are still incompletely known. Strategies to improve detection and diagnosis are needed, and treatment options, principally avoidance, are limited. A workshop recommended: a population-based study to more accurately document the incidence and prevalence of HP; better classification of disease stages, including natural history; evaluation of diagnostic tests and biomarkers used to detect disease; better correlation of computerized tomography lung imaging and pathologic changes; more study of inflammatory and immune mechanisms; and improvement of animal models that are more relevant for human disease.

Hypersensitivity pneumonitis: a multifaceted deceiving disorder

Hypersensitivity pneumonitis (HP) represents a group of immunologically mediated lung disorders provoked by recurrent exposure to various environmental agents. HP is multifaceted and may mimic almost any interstitial lung disease, some infectious diseases,and even bronchiolar disorders. In the absence of a diagnostic gold standard,diagnosis of HP requires a combination of clinical, environmental, radiologic, physiologic,and pathologic findings that represent a diagnostic challenge for clinicians and-in the chronic form-even for experienced pathologists. Therapeutic approach includes avoiding further exposure and, depending on the clinical form, the administration of a course of prednisone. New anti-inflammatory, immunoregulatory, and antifibrotic drugs are urgently needed for this and other interstitial lung diseases.

Clues for the differential diagnosis of hypersensitivity pneumonitis as an expectant variant of diffuse parenchymal lung disease

Hypersensitivity pneumonitis, also called extrinsic allergic alveolitis, a type of diffuse parenchymal lung disease (DPLD), is an immunologically mediated pulmonary disease induced by inhalation of various antigens. As data on the frequency of hypersensitivity pneumonitis are lacking in Turkey, a retrospective analyses was performed in 43 patients with DPLD, followed up over seven years. The objective was to discover cases fulfilling the diagnostic criteria for hypersensitivity pneumonitis, to determine the frequency and/or the new characteristics of the disease, and to pick up clues for differentiating it from other DPLDs. The four subjects with hypersensitivity pneumonitis (9%) who lived in an urban area were studied in detail. The most common symptoms were dry cough and dyspnoea. According to the symptom duration, clinical features, radiological and pathological findings, three were diagnosed with chronic and one with subacute hypersensitivity pneumonitis. Patients with hypersensitivity pneumonitis and those with DPLD were compared by means of age, sex, smoking status, symptom duration, haematology, erythrocyte sedimentation rate, peripheral cell count, spirometric parameters, blood gases, and diffusion capacity. No statistically significant difference was detected in these parameters except for forced expiratory volume in one second (FEV(1)) and forced vital capacity (FVC). In conclusion, patients with a history of antigen exposure, with mild symptoms such as dry cough and dyspnoea, and who have diffuse interstitial lung involvement on radiology should be carefully evaluated for hypersensitivity pneumonitis. Moreover, among other DPLDs, stable FEV(1) or FVC values may be the clues for establishing the diagnosis of hypersensitivity pneumonitis. However, further studies are needed in larger series of patients.

Aspects cliniques et immunopathologiques des pneumopathies d’hypersensibilité

INTRODUCTION

Hypersensitivity pneumonitis (HP) is a pulmonary disease with symptoms of dyspnoea and cough resulting from the inhalation of an antigen to which the patient has been previously sensitized.

STATE OF ART

Acute and subacute HP represent the most active forms of the disease which may become chronic while remaining progressive. HP may also evolve to end-stage lung disease. Clinical symptoms and signs tend to be non-specific and the diagnosis of HP often relies on the clinical context. The immune response is initiated when the alveolar macrophage phagocytoses the antigen, provoking the expansion of lymphocytes T and B that reach the pulmonary parenchyma through the systemic circulation. This reaction is amplified by the expression of a number of inflammatory mediators.

PERSPECTIVE AND CONCLUSION

This article summarizes our current understanding of the diagnostic approach and immunological mechanisms related to HP.

Effects of cigarette smoking on diagnostic tests for work-related hypersensitivity pneumonitis: data from an outbreak of lung disease in metalworkers

BACKGROUND

It is widely believed that development of hypersensitivity pneumonitis (HP) is forestalled in cigarette smokers. We encountered the largest outbreak of HP in metalworkers yet reported [Hodgson et al. (2001): Am J Ind Med 39:616-628] and subsequently did a chart review of the 61 patients seen in connection with the outbreak [Dangman et al. (2002a): Am J Resp Crit Care Med 165(8):A528; Dangman et al. (2002b): Am J Ind Med 42:150-162], developing a diagnostic index for this disease.

METHODS

A re-examination of data from the chart review was carried out to explore possible effects of cigarette smoking on the clinical tests used to diagnose HP [Hodgson et al. (2001): Am J Ind Med 39:616-628].

RESULTS

Cigarette smokers with HP were less likely than non-smokers with HP to develop crackles in the lungs, elevated erythrocyte sedimentation rates (ESRs), and restrictive spirometry. Smoking habits had little effect on diffusion capacity and alveolar-arterial oxygen gradients in the patients with HP. Smokers were more likely to have abnormal gallium scans than non-smokers.

CONCLUSIONS

It appears that cigarette smoking can affect the physical examination findings, spirometry, and ESR changes associated with HP, making these tests less sensitive and specific, and potentially obscuring the diagnosis. Such changes may contribute to the apparent "protective" effect of smoking on the development of HP.

Clinical diagnosis of hypersensitivity pneumonitis

The diagnosis of hypersensitivity pneumonitis (HP) is difficult and often relies on histopathology. Our objective was to identify diagnostic criteria and to develop a clinical prediction rule for this disease. Consecutive patients presenting a condition for which HP was considered in the differential diagnosis underwent a program of simple standardized diagnostic procedures. High-resolution computed tomography scan and bronchoalveolar lavage (BAL) defined the presence or absence of HP. Patients underwent surgical lung biopsy when the computed tomography scan, BAL, and other diagnostic procedures failed to yield a diagnosis. A cohort of 400 patients (116 with HP, 284 control subjects) provided data for the rule derivation. Six significant predictors of HP were identified: (1) exposure to a known offending antigen, (2) positive precipitating antibodies to the offending antigen, (3) recurrent episodes of symptoms, (4) inspiratory crackles on physical examination, (5) symptoms occurring 4 to 8 hours after exposure, (6) and weight loss. The area under the receiver operating characteristic curve was 0.93 (95% confidence interval: 0.90-0.95). The rule retained its accuracy when validated in a separate cohort of 261 patients. The diagnosis of HP can often be made or rejected with confidence, especially in areas of high or low prevalence, respectively, without BAL or biopsy.

An outbreak of hypersensitivity pneumonitis at a metalworking plant: a longitudinal assessment of intervention effectiveness

The authors describe a longitudinal assessment of intervention effectiveness in response to an outbreak of hypersensitivity pneumonitis (HP) at a metalworking facility. Thirty-five (29%) of the plant's 120 production workers were given a clinical diagnosis of HP during the two years of the investigation. Although quantitative exposure assessment tools were of limited utility, the investigators successfully used qualitative observations and the patients' return-to-work experiences to iteratively evaluate their exposure control recommendations. Recommended interventions included improving metalworking fluid management practices, enclosing selected metalworking fluid machining operations, eliminating mist cooling, exhausting two additional water-based industrial processes, increasing general dilution ventilation, and worker training. As of November 1999, 26 months into the outbreak, 51 percent (18) of the employees with a clinical diagnosis of hypersensitivity pneumonitis had been able to return to work. The symptom onset of the 35 workers who were given a clinical diagnosis of hypersensitivity pneumonitis during the two-year study period predated the implementation of the interventions. The collaboration of a multidisciplinary team appears to have allowed for successful intervention in this setting. A specific etiological agent(s) associated with the outbreak was not confirmed during the investigation. An acid fast isolate identified as being in the Mycobacterium chelonae group was detected in only one of the submitted metalworking fluid (MWF) sump samples. Longitudinally, there was a statistically significant difference in MWF sump bacteria (X(2) = 286.4, df = 17, p <.0001) and MWF sump fungi (X(2) = 28.1, df = 7, p <.0002). Measured oil mist air levels did not exceed the Occupational Safety and Health Administration's (OSHA's) permissible exposure limit (PEL), and in fact, did not exceed 0.5 mg/m(3).