Abstract
Reliable methods are needed to diagnose hypersensitivity pneumonitis. The aim of the study was to establish the diagnostic yield of specific inhalation challenge (SIC) in patients with hypersensitivity pneumonitis.
All patients with suspected hypersensitivity pneumonitis in whom SIC was performed (n=113) were included. SIC was considered positive when patients showed a decrease of >15% in forced vital capacity (FVC) or >20% in diffusing capacity of the lung for carbon dioxide, or a decrease of 10% to 15% in FVC accompanied by a temperature increase of 0.5°C within 24 h of inhalation of the antigen.
SIC was positive to the agents tested in 68 patients: 64 received a diagnosis of hypersensitivity pneumonitis and SIC results were considered false-positive in the remaining four patients. In the SIC-negative group (n=45), 24 patients received a diagnosis of hypersensitivity pneumonitis and SIC results were considered false-negative, and 21 patients were diagnosed with other respiratory diseases. The sensitivity and specificity of the test were 72.7% and 84%, respectively. Having hypersensitivity pneumonitis caused by an antigen other than birds or fungi predicted a false-negative result (p=0.001).
In hypersensitivity pneumonitis, positive SIC testing virtually confirms the diagnosis, whereas negative testing does not rule it out, especially when the antigenic sources are not birds or fungi.
Abstract
Specific inhalation challenge can be very useful for establishing the diagnosis of hypersensitivity pneumonitis http://ow.ly/zxszi
Footnotes
Support statement: This study was supported by FIS PI1001577 (Instituto de Salud Carlos III), Sociedad Española de Patología Respiratoria (SEPAR, Spanish Society of Respiratory Disease), and Fundacio Catalana de Pneumologia (FUCAP, Catalonian Pulmonology Foundation). M.J. Cruz is a researcher supported by the Miguel Servet programme from Instituto de Salud Carlos III (CP12/03101). The funders had no role in the study design, data collection or analysis, decision to publish, or preparation of the manuscript.
Conflict of interest: None declared.
- Received March 31, 2014.
- Accepted June 29, 2014.
- ©ERS 2014