Chest
Volume 157, Issue 6, June 2020, Pages 1506-1512
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Diffuse Lung Disease: Original Research
A Systematically Derived Exposure Assessment Instrument for Chronic Hypersensitivity Pneumonitis

Parts of this work were presented at the CHEST 2019 Annual Meeting, October 19-23, 2019, New Orleans, LA.
https://doi.org/10.1016/j.chest.2019.12.018Get rights and content

Background

Chronic hypersensitivity pneumonitis (CHP) is an immune-mediated interstitial lung disease (ILD) caused by inhalational exposure to environmental antigens, resulting in parenchymal fibrosis. By definition, a diagnosis of CHP assumes a history of antigen exposure, but only half of all patients eventually diagnosed with CHP will have a causative antigen identified. Individual clinician variation in eliciting a history of antigen exposure may affect the frequency and confidence of CHP diagnosis.

Methods

A list of potential causative exposures were derived from a systematic review of the literature. A Delphi method was applied to an international panel of ILD experts to obtain consensus regarding technique for the elicitation of exposure to antigens relevant to a diagnosis of CHP. The consensus threshold was set at 80% agreement, and median ≤ 2, interquartile range = 0 on a 5-point Likert scale (1, strongly agree; 2, tend to agree; 3, neither agree nor disagree; 4, disagree; 5, strongly disagree).

Results

In two rounds, 36/40 experts participated. Experts agreed on 18 exposure items to ask every patient with suspected CHP. Themes included CHP inducing exposures, features that contribute to an exposure’s relevance, and quantification of a relevant exposure. Based on the results from the literature review and Delphi process, a CHP exposure assessment instrument was derived. Using cognitive interviews, the instrument was revised by patients with ILD for readability and usability.

Conclusions

This Delphi survey provides items that ILD experts agree are important to ask in all patients presenting with suspected CHP and provides basis for a systematically derived CHP exposure assessment instrument. Clinical utility of this exposure assessment instrument may be affected by different local prevalence patterns of exposures. Ongoing research is required to clinically validate these items and consider their impact in more geographically diverse settings.

Section snippets

Identification of the Delphi Items

Potential exposure items for inclusion in an assessment instrument were identified through a systematic review of the literature. Electronic searches were performed though Medline, EMBASE, and the Cochrane Register of Controlled Trials from January 1, 1990, to April 30, 2019, using the following terms: “chronic hypersensitivity pneumonitis,” “fibrotic hypersensitivity pneumonitis,” “hypersensitivity pneumoni∗,” and “extrinsic allergic alveolitis.” Two reviewers (H.B., and J.L.) screened all

Systematic Literature Review

The systematic literature search yielded 38,001 citations; after screening, 922 citations were included in the final analysis (Fig 1). The most common reasons for exclusion included not involving HP patients, no exposure assessment performed or reported, and no cases presented (review or editorial). The review identified 60 unique exposures, of which 24 had more than five citations, and these were presented in the Delphi survey. An additional five exposure items were identified by experts and

Discussion

Through a systematic literature review, Delphi consensus of ILD experts, and patient validation process, we have developed an exposure assessment instrument for CHP containing a short, meaningful, and manageable list of exposures. This represents a systematic and methodologically robust approach to developing such an instrument, including theorization of a conceptual network and item development, adjustment of the conceptual network, authentication of the framework/pretesting and refinement of

Conclusion

This Delphi survey provides items that ILD experts agree are important to ask in all patients presenting with suspected CHP and provides a basis for a systematically derived CHP exposure assessment instrument. Ongoing research is required to validate these items in the clinical setting.

Acknowledgments

Author contributions: H. B. led the project, ethics adherence, data analysis, and manuscript preparation. All authors contributed to the concept and design of the project, data interpretation, manuscript synthesis, and revisions. H. B. had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Financial/nonfinancial disclosures: The authors have reported to CHEST the following: P. M. has, via his institution,

References (15)

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FUNDING/SUPPORT: This work was supported by a National Health and Medical Research Council PhD Postgraduate Scholarship and National Institutes of Health, National Heart, Lung, and Blood Institute [Grant K24HL127131].

Collaborators from the CHP Exposure Assessment are listed in the Acknowledgments.

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