According to the 2002 consensus report of the American Thoracic Society/European Respiratory Society (ATS/ERS), idiopathic pulmonary fibrosis (IPF) was classified as biopsy proven or probable IPF. Probable IPF is defined as those with distinctive features that allow for a confident diagnosis of IPF/usual interstitial pneumonia (UIP) within an appropriate clinical setting. The determination of the clinical course of probable IPF, as diagnosed by the ATS/ERS criteria, was studied.

Between March 1995 and August 2002, 36 patients with probable IPF, from two tertiary referral hospitals, were enrolled in this study. The clinical characteristics, prognostic factors and treatment efficacy of these patients were retrospectively evaluated.

The mean age of the subjects was 65 ± 6 years. The one and 3 year survival rates were 82.4 and 50.3%, respectively, and a median survival period of 42.0 months. The total cell count of bronchoalveolar lavage was higher in the death than the survival group (p<0.05). No survival benefits were found in the cytoxan and steroid treatment groups compared with other treatment groups.

These results suggest that the clinical course of probable IPF may be similar to that of biopsy-proven UIP. However, atypical patients must undergo an open lung biopsy for confirmation of the diagnosis.