Prevalence and patterns of inhalational exposures in patients with interstitial lung diseases: a cross-sectional study

Given the etiologic importance of inhalational exposures in specific interstitial lung disease (ILD) subtypes like hypersensitivity pneumonitis (HP) and pneumoconiosis, this study systematically evaluates exposure patterns across all ILD subtypes and assesses the utility of a standardized questionnaire for improved exposure identification. In this cross-sectional study, ILD patients were recruited between July 2023 and March 2024. Demographic, clinical, pulmonary function, radiological, and immunological parameters were recorded, and ILD subtypes were assigned by multidisciplinary discussion. Inhalational exposures were evaluated using a standardized questionnaire through in-person or telephonic interviews. Out of 139 total ILD patients, 107 (77%) reported at least one inhalational exposure, and 67 (48.2%) reported multiple exposures. These exposures were prevalent across multiple ILD subtypes beyond HP. Biomass (39.6%) and hay/grain (25.9%) were the most common. Blue-collar occupations were linked with higher odds of having any (81.8%) and multiple exposures (55.6%). Significant associations with HP were observed for animal hair and avian exposures, while tobacco smoke was associated with idiopathic pulmonary fibrosis. Having multiple exposures was associated with a significant reduction in forced vital capacity % predicted. Use of the standardized exposure questionnaire revealed more exposures per patient vs. routine history [median 1 (interquartile range 1-3) vs. 0 (interquartile range 0-1)], with 77% of participants classified as exposed vs. 41.7% by routine history (p<0.001). Inhalational exposures are widely prevalent across ILD subtypes, including those not classically exposure-related, and standardized exposure assessment using questionnaires improves their detection.