Chest X-rays in hypersensitivity pneumonitis: a metaanalysis of secular trend.

A metaanalysis of published reports of outbreaks of hypersensitivity pneumonitis was undertaken. A statistically significant substantial decline was seen in the sensitivity of chest X-rays (percent of positive in cases of disease) for the diagnosis of hypersensitivity pneumonitis over the years 1950-1980. Chest X-rays were also less likely to be abnormal where a population-based approach to the diagnosis of disease had been undertaken. Such declines in the diagnostic "sensitivity" of a test may be related to secular trends in knowledge and recognition of disease or to changes in the disease itself. Standardization of chest X-ray interpretation alone, even if successful, may not resolve the issue of accurate diagnosis of interstitial lung disease.