Environmental exposures common in people with pulmonary fibrosis

Among individuals with familial pulmonary fibrosis, environmental exposures are common, vary by sex and influence the CT pattern, timing of disease onset and mortality, researchers reported.

“Despite a linkage between exposures and specific interstitial lung disease diagnoses, remarkably little objective data exists as to the relationship between exposures and disease morphology or survival outcomes,” Carla R. Copeland, MD, pulmonologist at Vanderbilt University Medical Center, and colleagues wrote in Annals of the American Thoracic Society. “For example, several environmental exposures ... are consistently identified as risk factors for idiopathic pulmonary fibrosis, and a substantial proportion of individuals diagnosed with fibrotic hypersensitivity pneumonitis do not manifest the expected chest CT pattern.”

Researchers analyzed 159 patients with familial pulmonary fibrosis (mean age, 64.2 years; 61.6% men) from a prospective cohort at Vanderbilt University Medical Center. All patients completed an environmental exposure questionnaire and underwent chest CT. Researchers defined disease characteristics by chest CT lung parenchymal findings that were associated with fibrotic hypersensitivity pneumonitis or usual interstitial pneumonia and by time from birth to symptom onset or a composite of lung transplantation or mortality.

The findings were then validated in a cohort of 694 patients with sporadic pulmonary fibrosis (mean age, 62 years; 62.5% men) from the Lung Tissue Research Consortium (LTRC) study.

Sixty percent of patients were ever smokers.

Men had a lower likelihood of CT features of fibrotic hypersensitivity pneumonitis (adjusted OR = 0.27; 95% CI, 0.09-0.76; P = .01) compared with patients from the LTRC study (aOR = 0.35; 95% CI, 0.21-0.61; P = .0002).

Organic exposures were not consistently associated with fibrotic hypersensitivity pneumonitis features in either cohort.

Transplant-free survival in ever smokers was shorter for patients with familial pulmonary fibrosis (aHR = 1.64; 95% CI, 1.07-2.52; P = .02). Male sex was not associated with differential survival (aHR = 0.75; 95% CI, 0.5-1.14; P = .18).

Researchers reported smoking was a risk factor for honeycombing among patients with familial pulmonary fibrosis (aOR = 2.19; 95% CI, 1.12-4.28; P = .02) and those from the LTRC study (aOR = 1.69; 95% CI, 1.22-2.33; P = .002). Exposure to rock dust may also be linked to honeycombing, but this association was not significant when the researchers accounted for sex and smoking status in patients with familial pulmonary fibrosis (aOR = 2.27; 95% CI, 0.997-5.15; P = .051) and those from the LTRC study (aOR = 1.51; 95% CI, 0.97-2.33; P = .07), the researchers wrote.

“The role of sex and exposures in the development of pulmonary fibrosis should be the focus of future research,” the researchers wrote.