Time of exposure as a prognostic factor in avian hypersensitivity pneumonitis

Spirometric values were subsequently evaluated in 22 patients suffering from hypersensitivity pneumonitis caused by avian problems. First spirometric values were abnormal in 18/22 (82%) of patients. A restrictive pattern was observed in 16/22 (72%) of patients and an obstructive pattern in 6/22 (27%). The TLCO was reduced in all cases (12/12). Improvement or normalization of the respiratory function occurred 3.4 +/- 2.4 months after the avian contact had ceased. At the end of the follow-up, parameters were normal in 13/22 (59%) of patients. The restrictive pattern remained unchanged in 7/22 (32%), and the obstructive pattern persisted in 4/22 (18%) of the patients. The TLCO was normal in 6/12 (50%) of patients. Neither age nor treatment with corticosteroids (13 patients) had a significant influence upon the evolution of the lung function. However, total recovery or significant improvement was observed in 12/12 (100%) of patients who had been in contact with birds less than 2 years, in contrast to 6/10 (60%) of patients with more than 2 years of contact (P = 0.002).