The presence of interstitial lung abnormalities are associated with a greater risk of all-cause mortality, according to a study in JAMA.
Interstitial lung abnormalities are defined as specific patterns of increased lung density noted on chest computed tomography (CT) scans identified in participants with no prior history of interstitial lung disease (a large group of disorders characterized by progressive scarring of the lung tissue between and supporting the air sacs). In studies of adults, interstitial lung abnormalities are present in approximately 2 percent to 10 percent of research participants (and 7 percent of a general population sample) and are associated with reductions in lung capacity and exercise capacity.
Ivan O. Rosas, M.D., of Brigham and Women's Hospital, Harvard Medical School, Boston, and colleagues examined whether interstitial lung abnormalities are associated with increased mortality. The study included 2,633 participants from the FHS (Framingham Heart Study), 5,320 from the AGES-Reykjavik Study (Age Gene/Environment Susceptibility), 2,068 from the COPDGene Study (Chronic Obstructive Pulmonary Disease), and 1,670 from ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints).
Interstitial lung abnormalities were present in 7 percent of the FHS participants, 7 percent from AGES-Reykjavik, 8 percent from COPDGene, and 9 percent from ECLIPSE. Over median follow-up times of approximately 3 to 9 years, there were more deaths (and a greater absolute rate of mortality) among participants with interstitial lung abnormalities when compared with those who did not have interstitial lung abnormalities: 7 percent vs 1 percent in FHS, 56 percent vs 33 percent in AGES-Reykjavik, and 11 percent vs 5 percent in ECLIPSE. Interstitial lung abnormalities were associated with a higher risk of death in all groups. In the AGES-Reykjavik cohort, the higher rate of mortality could be explained by a higher rate of death due to respiratory disease, specifically pulmonary fibrosis. The associations between interstitial lung abnormalities and mortality were not lessened after adjustment for smoking, cancer, COPD, or coronary artery disease.
"These findings, in conjunction with those previously published, demonstrate that despite often being undiagnosed and asymptomatic, interstitial lung abnormalities may be associated with lower survival rates among older persons," the authors write. "The clinical implications of this association require further investigation."
"Follow-up studies should determine the risk factors for and the events that lead to death among persons with interstitial lung abnormalities. Given the ability to treat more advanced stages of pulmonary fibrosis, future clinical trials attempting to reduce the overall mortality associated with pulmonary fibrosis should consider including early stages of the disease."