The disease is characterized by the insidious onset of dyspnea or cough and usually evolves slowly.

Now, Selman and coworkers present in an article published in the online, open-access journal PLoS ONE, strong evidence indicating that a subset of IPF patients has a short duration of symptoms before diagnosis and display an accelerated clinical course to end-stage disease. The authors postulate that these "rapid progressor" patients, predominantly smoking males, represent a distinct clinical phenotype compared with the usual "slow progressors" patients.

"These findings highlight the variability in the progression and outcome of IPF, and may explain, in part, the difficulty in obtaining significant and reproducible results in studies of therapeutic interventions in patients with IPF," said Dr Selman, who is the Director of Research at the National Institute of Respiratory Research in Mexico City and the lead author on this publication. "They also suggest that physicians should pay more attention to the time of onset of symptoms, and to look for other signs that allow the identification of these rapid progressor patients".

In this study the authors performed global gene expression analysis and other molecular studies in a subset of patients and identified a number of genes that were differentially expressed in both groups, suggesting that rapid progressors are biologically distinct from slow progressors.

"While preliminary, these results may allow investigators to identify biomarkers of disease progression," said Dr King, who is the Chief of Medicine at San Francisco General Hospital and an internationally renowned expert in research and management of pulmonary fibrosis.

The senior author on this paper, Dr Naftali Kaminski, who is the Director of the Simmons Center for Interstitial Lung Disease at the University of Pittsburgh, added that this research highlighted the need to collect as much information on patients with IPF as possible. "We are only now starting to really understand the disease and characterize it," he said, "therefore, it is critical for patients with the disease to be seen in centers that are actively involved in IPF research."

Better identification and understanding of these differences may provide insights into the pathogenesis of IPF and assist in the development of therapeutic interventions for this devastating lung disease.

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