Insights on identification, remediation of environmental exposures in patients with ILD

A review published in Chest highlights the need for a standardized method to identify and categorize patients’ environmental exposures to aid in the diagnosis and prevention of interstitial lung disease progression.

“While hypersensitivity pneumonitis and pneumoconiosis are archetypal environmental lung diseases, environmental exposures likely contribute to the pathogenesis of some idiopathic interstitial pneumonias, including idiopathic pulmonary fibrosis,” Carla R. Copeland, MD, clinical fellow in the department of medicine in the division of allergy, pulmonary and critical care medicine at Vanderbilt University Medical Center, and colleagues wrote. “... There is no standardized approach to evaluation for or remediation of potentially harmful environmental exposures in home or workplace environments for patients with hypersensitivity pneumonitis or other ILDs.”

Copeland and colleagues reviewed evidence for environmental contributions to ILD pathogenesis and evaluated literature and clinical cases to describe the potential utilization of professional evaluation for environmental factors that may contribute to the ILD progression and development.

ILD, environmental exposures

Prior research has linked risk for idiopathic pulmonary fibrosis, hypersensitivity pneumonitis and other ILDs with specific environmental exposures or occupations. And, in those with certain ILDs, exposure to dusts and other pollutants may have a more rapid onset of disease and worse outcomes.

“A key component of the diagnostic evaluation for environmental lung disease includes elucidation of a compatible exposure history; without this information, the diagnosis may remain in question,” the authors wrote.

However, they noted, “scant evidence specific to ILD guides identification and management of these exposures.”

Therefore, standardized tools to improve environmental assessment in ILD are needed, according to Copeland and colleagues.

Exposure assessment

“Physician inquiry into the plethora of potentially harmful environmental exposures associated with various ILDs can be time consuming, making development of a standardized questionnaire, to facilitate patient self-reporting of exposures, appealing,” the authors wrote.

Environmental exposure questionnaires administered to patients have been used to determine environmental risk factors for IPF development in various studies, but, currently, no questionnaire has been validated, according to the authors.

“From a diagnostic standpoint, current hypersensitivity pneumonitis diagnosis guidelines recognize that the use of questionnaires may be beneficial in obtaining a thorough exposure history and suggest that exposure questionnaire development and validation should be a focus of future research,” the researchers wrote.

The authors noted that job exposure matrices are another possible tool to determine associations between specific exposures and the risk for disease onset or progression. In job exposure matrices, an expert obtains patient-reported job titles, occupations, industries and work tasks to assess specific exposures and the intensity of each exposure. Job exposure matrices have been developed for patients with COPD and asthma, but there are not currently job exposure matrices specific for ILD, according to the authors.

For patients without exposures associated with ILDs, some may require an environmental evaluation by a trained professional such as industrial hygienists, indoor environmental quality consultants and environmental health professionals.

Identification, remediation

Previous studies demonstrated serum testing for antigen-specific immunoglobulin G antibodies as beneficial in identifying specific disease-causing exposures. However, this method in an individual patient or in situations where exposures are not identified may prove to be difficult, according to the authors.

Although this type of testing may benefit individuals when exposures are not identified in patients’ history, because there are no well-established or validated exposure thresholds for disease development, interpretation of environmental inspection may be challenging, the authors wrote.

“Antigen avoidance with assessment for clinical improvement over time is proposed as an indirect way of determining the inciting environment,” the authors wrote. “However, the optimal duration of exposure avoidance necessary to observe beneficial effects is unknown and could be particularly difficult in fibrotic ILD where the benefit may be slowed disease progression rather than objective improvement.”

In individuals with asthma, home evaluation and remediation of triggers demonstrated benefit. In one systematic review, it was associated with decreased symptom burden, improved quality of life and decreased health care utilization in those adhering to home-based environmental assessments and interventions. More in-depth environmental evaluation to determine exposures requiring remediation may be needed among individuals with ILD, the authors wrote.

A small pilot study focused on the feasibility of identifying causative antigens in the home and/or workplace among 19 patients with hypersensitivity pneumonitis using questionnaires, targeted environmental sampling and testing patient serum against antigens collected. This study suggested environmental evaluation in hypersensitivity pneumonitis may be the most productive as a diagnostic intervention early in the disease course and at the time of active exposure.

In addition, cost to the patient should be considered when researching environmental evaluation and remediation in terms of payment for professional services and interference with livelihood as U.S. insurances generally do not cover environmental evaluations.

Looking ahead

The authors recommend further research in all areas pertaining to patients with ILD. Areas for further research might include identifying the most beneficial ways to categorize the relevance of specific exposures in diagnosing ILD and to optimize interventions to harmful ILD exposures.

“Future studies should focus on the feasibility, long-term outcomes and cost-effectiveness of various domestic remediation strategies in both non-fibrotic and fibrotic ILDs,” the authors wrote. “Furthermore, deeper investigation into genetic factors, biomarkers and environmental cofactors that may make an individual more susceptible to specific exposures is required. Further investigation is also needed in determining whether the type or amount of an exposure alters clinical course or prognosis in hypersensitivity pneumonitis and other ILDs.”