BACKGROUND:

Idiopathic pulmonary fibrosis is a progressive and generally fatal disease that causes fibrosis of the pulmonary interstitium. While many environmental agents cause diseases clinically similar, the etiology of idiopathic pulmonary fibrosis suggests that environmental agents could incite the tissue injury that results in the disease; furthermore, host characteristics could have an important role in determining the magnitude of the host response to the agent initiating injury.

DESIGN NARRATIVE:

In this case control study, cases were ascertained at the multiple collaborating centers and controls were identified by telephone screening.

A telephone interview was conducted to collect information needed to test hypotheses concerning cigarette smoking, occupational exposure, indoor exposures, other environmental factors, and host factors. To limit disease misclassification, two pathologists experienced with interstitial diseases of the lung reviewed histopathological material from all cases to exclude entities other than interstitial lung fibrosis and to fully characterize the cases clinically. The mortality of this large series of cases was also described.