Environmental Exposures, Characteristics, and Treatment Outcomes of Hypersensitivity Pneumonitis at a Rural Appalachian Academic Medical Center: A Cross-sectional Study

Purpose: Hypersensitivity pneumonitis (HP) is a form of interstitial lung disease (ILD) caused by inhalational exposure to an antigen. Little is known about the exposures, outcomes, and management of HP in rural Appalachian patients. Methods: A retrospective cross-sectional study was conducted from January 1, 2017, to June 30, 2022, at a tertiary academic medical center. Sixty-two patients were initially screened, and seven patients fulfilled the inclusion criteria. The primary outcome was the exposure leading to HP. Secondary outcomes included the disease stage at diagnosis, smoking rate, treatment modalities, ILD exacerbation rate, and mortality. Results: Birds and mold are the more common exposures attributed to HP (both n=2, 28.57%). Novel exposures to continuous positive airway pressure devices, vapor and/or fumes, and fiberglass were noted (each n=1, 14.28%). Three patients (42.85%) had fibrotic HP at presentation. Most patients were ever-smokers (n=4, 57.14%). All patients (n=7, 100%) received corticosteroids with a mean duration of use of 2.50 ± 0.65 months, and a mean dose of 37.14 ± 12.54 mg. One (14%) patient was compliant with antigen elimination. ILD exacerbation and mortality rate was high (both n=2, 28.57%). Conclusion: The exposures identified in rural Appalachian HP patients were similar to other rural and urban populations in the United States. Risk factors associated with poor outcomes, such as smoking, fibrotic HP subtype, and non-avoidance of antigen were higher in this cohort. The rate of ILD exacerbation and mortality were similarly higher. Larger studies are needed to investigate longitudinal trends of exposure, characteristics, and management of HP to improve outcomes in rural populations.