Assessment of Clinical Relevance of Antigen Improves Diagnostic Accuracy of Hypersensitivity Pneumonitis

Abstract

Abstract Background Exposure assessment is integral to the diagnosis of hypersensitivity pneumonitis (HP). Although the clinical relevance of exposed antigens is essential for the assessment, many of the previous guidelines or reports have only evaluated a simple exposure history or immunological test. To overcome this problem, the Exposure Assessment Form (EAF) was developed as an assessment tool for classifying the exposure grade from G0 to G4. The EAF was modified from the description in the HP guidelines published by the Japanese Respiratory Society. Methods One hundred and seventy-two consecutive patients with interstitial lung disease who underwent multidisciplinary discussion (MDD) at our hospital were retrospectively examined. We assessed whether the use of the EAF improved the performance of guidelines in the diagnosis of HP. We also evaluated whether the exposure grade affected the prognosis of HP. Results Even when HP diagnosis with a confidence of 70% or higher was made according to the international guideline, almost half of these cases had different final diagnoses with exposure grades of G0, G1, or G2. When the result of the EAF was integrated into the exposure definition of the international guideline, the specificity of the diagnostic performance improved, while sensitivity was maintained. Furthermore, HP patients with an exposure grade of G3 or higher showed tendency for longer time to initiate drug treatment. Conclusions This is the first study to evaluate the clinical relevance of possible antigens using the EAF. Assessing the exposure grade prevents overdiagnosis and improves the diagnostic performance of the guideline.