Development and validation of the Hypersensitivity Pneumonitis South Asian Questionnaire for Exposure (HP-SAQE): a novel, qualitative and quantitative tool

INTRODUCTION: There is an unmet need for a validated qualitative and quantitative tool to assess environmental exposures in patients with interstitial lung disease (ILD). This study aimed to develop and validate a comprehensive tool to systematically identify exposures in patients with ILD. METHODS: A systematic literature search was completed to identify exposures associated with more than five documented hypersensitivity pneumonitis (HP) cases. These exposures were evaluated through a two-round Delphi survey involving 39 pulmonologists from India, Sri Lanka, Pakistan and Nepal. The questionnaire was prospectively derived at one centre and validated across five centres in India and Sri Lanka. The HP South Asian Questionnaire for Exposure (HP-SAQE) was validated against the gold standard multidisciplinary discussion diagnosis, distinguishing HP from non-HP ILD. RESULTS: The literature search screened 5170 records and included 407 studies, identifying 24 exposures. A 50-item Delphi survey achieved expert consensus (>70%) on 17 qualitative and 4 quantitative items (six questions) by 39 pulmonologists. HP-SAQE score ranged from 0 to 14. After pilot testing, the questionnaire was translated into Hindi, Tamil and Sinhala. In the derivation cohort (n=40), the HP-SAQE score was significantly higher in patients with HP versus non-HP (mean: 10.2±1.6 vs 6.7±4.2; p=0.001). This finding was validated in a separate cohort (n=163; mean: 9.4±2.2 vs 4.13±4.28; p