Clinical, Radiological and Pathological Characteristics of Hypersensitivity Pneumonitis and its Association with the Duration of Exposure in a Tertiary Centre

Abstract

Background: Hypersensitivity pneumonitis (HP) has varied presentation, and it is unknown as to which individuals exposed to a potential antigen will develop HP. HP can often progress to permanent lung fibrosis, with significant social and economic consequences, besides reduced survival. To the best of our knowledge, this is the first such paper from India comparing characteristics of HP with duration of exposure.

Methods and Materials: A retrospective observational study was conducted on 60 adult patients who meet the criteria of Hypersensitivity pneumonitis according to Schuyler’s criteria, at a tertiary care centre between February 2022 to June 2023. Clinical data including patient’s history, clinical manifestation, laboratory findings and HRCT findings was obtained from patient’s medical record files.

Results: 73.3% patients were female. Most common offending antigen was avian droppings. In 11.7% the antigen could not be identified. 56.7% were homemakers. The most common HRCT finding was ground glass haziness (90%) and most common radiological pattern was Fibrotic Non-specific Interstitial pneumonitis (NSIP).71.67% patients had a restrictive ventilatory defect.90% had chronic HP. Longer the duration of exposure, more severe is the restriction and less distance was covered on 6minute walk test(6MWT). With increasing duration of exposure, more patients developed Unique interstitial pneumonitis (UIP) pattern rather than fibrotic or cellular NSIP.

Conclusion: Continued long-term exposure causes most patients to develop parenchymal fibrosis. Longer duration of exposure is associated with worse ventilatory parameters and outcomes.