Relation Between Interstitial Lung Abnormalities and Mortality

Interstitial lung abnormalities were strongly associated with an increased risk of death, according to a prospective analysis of four separate research cohorts.

Interstitial lung abnormalities are a group of disorders which involve lung inflammation or scarring of the lung tissue between and supporting the air sacs, which could lead to lung stiffness and could also affect your breathing abilities in the long run. Rheumatologic or autoimmune diseases are some of the known causes of interstitial lung diseases.

Interstitial lung abnormalities are commonly seen in older individuals and are thought to lead to early stages of pulmonary fibrosis. In one of the studies, these abnormalities have been linked to reductions in lung capacity, exercise capacity, gas exchange, amongst others.

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‘Interstitial lung abnormalities on CT scans signal higher-than-average mortality within 3-9 years.’

According to a recent study published in the Journal of the American Medical Association, interstitial lung abnormalities were strongly associated with an increased risk of death.

Lead author Rachel K. Putman, M.D., from the Brigham and Women's Hospital in Boston, and her associates analyzed data from four prospective cohort studies to investigate whether interstitial lung abnormalities are associated with increased mortality.

The study participants were middle-aged to older people from four separate research cohorts as follows:

2,633 from the Framingham Heart Study (FHS)
5,320 from the Age Gene/Environment Susceptibility (AGES)-Reykjavik Study
2,068 from the Chronic Obstructive Pulmonary Disease (COPD) Gene study
1,670 from the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) study

Status of interstitial lung abnormality was determined by chest CT evaluation. These imaging abnormalities (which included reticular abnormalities, diffuse centrilobular nodularity, non-emphysematous cysts, honeycombing, traction bronchiectasis, amongst others) were evaluated as specific patterns of increased lung density affecting more than 5% of any lung zone.

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It was seen that interstitial lung abnormalities were found to be present in 177 (7%) of the participants from FHS, 378 (7%) in the AGES-Reykjavik study group, 156 (8%) in COPD Gene group, and in 157 (9%) participants from ECLIPSE study.

The authors reported that the presence of interstitial lung abnormalities were linked to a greater risk of death in all four cohorts over a median follow-up times ranging from 3 to 9 years when compared with those who did not have interstitial lung abnormalities. This was seen after adjustment was made for smoking, chronic obstructive pulmonary disease (COPD), cancer and other co-existing conditions.

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The AGES-Reykjavik study was the only study to assess causes of death and the higher rate of mortality seen in this group could be explained by a higher rate of death due to respiratory disease (13%), particularly pulmonary fibrosis.

Putnam and his associates reported in the journal JAMA that the pattern of abnormalities may be an important risk factor for death in older populations, rather than being merely a precursor to more advanced fibrosis.

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The authors stated, "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."

They noted that while additional studies were needed to confirm the findings and to determine the risk factors for interstitial lung abnormalities and the events that lead to the death of the patient.

The authors commented, "Although the survival rate of people with idiopathic pulmonary fibrosis (IPF) appears to have increased slightly in recent years, median survival times after diagnosis is 3 to 5 years, which is worse than that of most malignancies. Given the other correlations between IPF and interstitial lung abnormalities, we hypothesized that the presence of interstitial lung abnormalities would be associated with an increased rate of mortality."

The results of the study could have significant implications for clinical practice and research, however requires further investigation.

References:

1. http://jama.jamanetwork.com/article.aspx?articleid=2491637

2. http://www.mayoclinic.org/diseases-conditions/interstitial-lung-disease/basics/definition/con-20024481

3. http://www.chestphysician.org/specialty-focus/pulmonary-medicine/article/interstitial-lung-abnormalities-linked-to-higher-mortality/b7d7236095ae3a3ad5201ce6ff8c1d2a.html

Source-Medindia