Jim Kling

September 15, 2014

MUNICH — Some cases of idiopathic pulmonary fibrosis (IPF) may be due to environmental or occupational exposure to asbestos, according to a new analysis of mortality data in England and Wales. This suggests that patients with known asbestos exposure, currently excluded from treatment with new IPF drugs, may need to be considered candidates for these drugs, report researchers.

"IPF and asbestos can be quite difficult to untangle," said presenter Carl Reynolds, MBBS, MSc, an honorary fellow at Imperial College London. "You have the same pattern of usual interstitial pneumonitis seen radiologically in both conditions."

Asbestos could theoretically cause symptoms similar to IPF, but the relationship is unproven. "Some have argued for it," Dr. Reynolds told Medscape Medical News here at the European Respiratory Society (ERS) International Congress 2014, "but nobody has really gone any farther to show that maybe a proportion of IPF is due to asbestosis."

To test the idea, Dr. Reynolds and his colleagues used data from the Office of National Statistics to look at associations between IPF, asbestosis, and mesothelioma mortality in England and Wales between 1974 and 2012.

The estimated number of deaths from IPF in men increased from fewer than 500 in 1974 to more than 2000 by 2012. The numbers increased at a similar rate in women.

When the researchers looked at mesothelioma and asbestosis, they found a similar rising trend in mesothelioma, but relatively little increase in deaths from asbestosis.

 
I aim to have an answer as to whether or not there's a dose-responsive relationship between asbestos exposure and IPF. Dr. Carl Reynolds
 

High rates of IPF deaths were seen in particular regions in the North West and South East of England, which have a history of shipyard work and therefore potential exposure to asbestos dust.

Next, Dr. Reynolds hopes to prove a connection by conducting a hospital-based case-controlled study of IPF patients in which he will take detailed histories of each patient to determine asbestos exposure.

"I aim to have an answer as to whether or not there's a dose-responsive relationship between asbestos exposure and IPF," he said.

Asbestosis epidemiology has changed, according to Sherwood Burge, MD, who runs the occupational lung disease services for the West Midlands in the United Kingdom, at Birmingham Heartlands Hospital, and who attended Dr. Reynold's presentation.

More Interstitial Pneumonitis

At its height in the 1980s, asbestosis was characterized by severe cases. That phase has passed, largely because most of the patients died. "Then we had a lull, with much less asbestosis," said Dr. Burge.

But things are changing. There has been an uptick in interstitial pneumonitis, the histopathology of which resembles both asbestosis and IPF. "Now, we're seeing people who have a history of asbestos exposure," said Dr. Burger. "They have much more than average exposure to asbestos, but much, much less exposure than we used to believe was required to develop asbestosis. Now they are presenting with usual interstitial pneumonitis. Some people use to call that IPF, but I think you can make a reasonable case that some are due to asbestos."

That is an important distinction in light of the new drugs becoming available to treat IPF. The new study suggests that there are patients with an IPF-like condition due to asbestos exposure who might benefit from IPF drugs.

"I don't see why not," Dr. Burge said, when asked if the drugs should be considered for those patients.

Asbestosis cases continue to rise — a surprise, given that asbestos was phased out of many industries.

"At least in the UK, asbestos exposure essentially stopped in 1980," said Dr. Burge. "The fact that asbestosis is going up implies that you can't model that on recent exposure; there has to be something in the past, and it has to be duration of exposure to asbestos to account for this increase."

Dr. Reynolds and Dr. Burge have declared no relevant financial relationships.

European Respiratory Society (ERS) International Congress 2014: Abstract 3205. Presented September 9, 2014.

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