The following is a summary of “Antigen identification and avoidance on outcomes in fibrotic hypersensitivity pneumonitis” published in the October 2022 issue of Respiratory by Petnak et al.

The suspected cause-causing antigens may not be found in 30–50% of patients with fibrotic hypersensitivity pneumonitis (f-HP). It isn’t clear if identifying and avoiding antigens in this situation has any additional clinical benefits. Researchers thought that figuring out what antigens are and avoiding them might help patients with the fibrotic disease. Patients who met recent international practice guidelines for f-HP diagnosis and were seen at the Mayo Clinic Rochester between January 2005 and December 2018 were included. By looking at the medical records, the causative antigen and how to avoid antigens were clearly defined and determined. A Cox proportional-hazards regression was used to see how well antigen identification and avoidance predicted death from any cause or lung transplantation.

A total of 377 patients were counted. About 60%, or 225, of these cases, had a suspected cause-related antigen. Identification of a suspected antigen (adjusted hazard ratio (HR) 0.69, 95% confidence interval (CI) 0.48–0.99; P=0.04) and subsequent avoidance of the antigen (adjusted HR 0.47, 95% CI 0.31–0.71; P<0.001) were linked to a decrease in all-cause mortality and transplantation. Both those with suspected antigen identification but non-avoidance and those with unidentifiable antigen had a higher risk of all-cause mortality or transplantation (adjusted HR 2.22, 95% CI 1.34–3.69; P=0.002 and adjusted HR 2.09, 95% CI 1.34–3.26; P=0.001, respectively). 

Exposure to avian antigens was linked to a better outcome than other antigen subtypes (adjusted HR 0.63, 95% CI 0.43–0.93; P=0.02). The results suggest that antigen identification and antigen avoidance are still important, even for people with the fibrotic disease, where both seem to be related to better outcomes.