Abstract
Background: Recurrent attacks of hypersensitivity pneumonitis (HSP) in response to avian antigens can lead to diffuse parenchymal lung disease (DPLD) with rapid decline in lung function.
Aims and Objectives: To identify avian specific IgG titer/cut-off value in HSP-DPLD.
Methods: We performed a retrospective analysis on patients from Eastern India all of whom had history of avian exposure. This exposure was tested using Ge91 ImmunoCAP mixture of pigeon serum, feathers and droppings (Thermo Fisher Scientific, Sweden). Thereafter, patients were classified as either “probable or likely chronic HSP” or 'unlikely HSP” using clinical data, HRCT changes and avian IgG level.
Results: Records of 61 patients (34 females, 27 males) with median age 55 years (range 10-85 years) were analysed. Dyspnoea and cough were present in all patients. 26 patients (42.6%) were diagnosed as 'probable or likely chronic HSP'-induced DPLD with HRCT findings of traction bronchiectasis/honey combing had avian precipitin IgG levels between 32.5 and >200mgA/L (median 71.6, IQR25-75, 75.1-94.4 mgA/L), while 35 patients with 'unlikely HSP' (reticular changes only) had median avian IgG level 20.5 mgA/L (range 0.01-36.2 mgA/L). The difference in medians was highly significant (p<0.0001). Seven patients with avian IgG >200mgA/L had extensive honey combing on HRCT (usual interstitial pneumonia pattern). Avian specific IgG level cut-off at 30mgA/L had 100% sensitivity with 82.86% specificity.
Conclusions: Avian precipitin IgG levels >30 mgA/L with supporting clinical history and usual interstitial pneumonia pattern on HRCT identifies patients with diffuse parenchymal lung disease due to avian hypersensitivity pneumonitis.
- Copyright ©the authors 2016