Farmer's lung disease: Analysis of 75 cases

Introduction: Farmer's lung disease (FLD) is a common form of hypersensitivity pneumonitis possibly underdiagnosed in our midst. The aim of this study was to describe clinical characteristics, evolution and factors that influence the prognosis of patients with FLD.

Patients and methods: A retrospective study that included all patients diagnosed with FLD presenting an environmental exposure risk, a clinic, lung function and a compatible radiology, in which antigen sensitisation was demonstrated and/or a concordant pathology.

Results: We selected 75 patients with FLD, 50 with acute or subacute form (ASF) and 25 with chronic form (CF). Forty-four percent of patients (n=33) were diagnosed during the months of March and April, especially those with ASF compared to CF (52 vs. 28%; P=.0018). In the ASF group, DLco showed an improvement during follow-up (P=.047). The determination of specific IgG antibodies was positive in 39 patients (78%) with ASF (44% of them against Aspergillus) and CF 12 (48%). The realisation of antigenic avoidance (OR 9.26, 95% CI 1.3-66.7, P=.026) and the administration of immunosuppressive therapy (OR 16.13, 95% CI 1.26-200, P=.033) were predictors of better disease progression.

Conclusions: FLD is predominantly seasonal in our environment. CF usually has a negative specific IgG antibodies unlike ASF, where antibodies against Aspergillus are the most common. The realisation of antigenic avoidance and immunosuppressive treatment are possible predictors of better disease progression.