Hypersensitivity pneumonitis: Clinical manifestations-Prospective data from the interstitial lung disease-India registry

Context: Multiple environmental factors are associated with development of hypersensitivity pneumonitis (HP), and diagnostic algorithms for the diagnosis of HP have been proposed in recent perspectives. Aims: We analyzed the data of patients with HP from interstitial lung disease (ILD)-India registry. The analysis was performed to (1) find the prevalence of HP, (2) reclassify HP as per a recently proposed classification criterion to assess the level of diagnostic certainty, and (3) identify the causative agents for HP. Setting and Designs: This was a prospective multicenter study of consecutive, consenting adult patients with new-onset ILD from 27 centers across India (March 2012-April 2015). Materials and Methods: The diagnoses were based on prespecified working clinical criteria and multidisciplinary discussions. To assess strength of diagnosis based on available clinical information, patients with HP were subclassified into definite HP, HP with high level of confidence, and HP with low level of confidence using a recent classification scheme. Results: Five hundred and thirteen of 1084 patients with new-onset ILD were clinically diagnosed with HP and subclassified as HP with high level of confidence (380, 74.1%), HP with low level of confidence (106, 20.7%), and definite HP (27, 5.3%). Exposures among patients with HP were birds (odds ratios [OR]: 3.52, P < 0.001), air-conditioners (OR: 2.23, P < 0.001), molds (OR: 1.79, P < 0.001), rural residence (OR: 1.64, P < 0.05), and air-coolers (OR: 1.45, P < 0.05). Conclusions: About 47.3% of patients with new-onset ILD in India were diagnosed with HP, the majority of whom were diagnosed as HP with a high level of confidence. The most common exposures were birds, cooling devices, and visible molds.