Please use this identifier to cite or link to this item: http://hdl.handle.net/1946/27507
Interstitial lung abnormalities and aging
Gísli Þór Axelsson
Introduction: Idiopathic pulmonary fibrosis (IPF) is an incurable disease characterized by fibrotic changes in the pulmonary interstitium leading to death due to respiratory failure. Interstitial lung abnormalities (ILA) are radiological changes similar to IPF, but less prominent and most often in asymptomatic individuals. They are perceived to be a precursor of IPF in a small proportion of ILA cases, since their prevalence is much greater than of IPF. Increasing age is one of the main risk factors for both these conditions, prompting the question of whether processes related to aging could be related to the pathogenesis of ILA and IPF. The aim of the thesis was to examine the associations of biomarkers of aging with ILA to better understand the relationship of aging and fibrosis of the lungs.
Materials and methods: Data were used from the AGES-Reykjavik study, a prospective, epidemiological study of 5,764 elderly people in Iceland designed to improve understanding of aging. CT scans of the participants had been previously evaluated for ILA status by readers blinded to participant information. The proposed biomarkers of aging were the inflammatory markers; CRP and albumin and markers of red blood cells; red blood cell count, hemoglobin and hematocrit. In addition, markers of physical function; grip strength, knee extension strength, usual gait speed, the timed up and go test and thigh muscle mass were included. The associations of these variables to ILA and subtypes of ILA were examined using logistic regression modelling. In addition, the associations of ILA with markers of participants’ health; independence in activities of daily living (ADL), general health status and physical activity, were explored.
Results: In models adjusted for all covariates, both inflammation markers, CRP and albumin, were associated with ILA, as well as all the functional markers except for the timed up and go test. Markers of red blood cells were not associated with ILA. CRP and albumin had a slightly larger effect on ILA status than the functional markers, as measured by ORs between the first and third quartiles of explanatory variables. Of subtypes of ILA, most of the significant markers were associated with subpleural abnormalities and mixed abnormalities. All markers of participants’ health were associated with ILA, with the largest OR being that of poor general health status.
Conclusions: This study found an association between ILA and markers of aging such as CRP, albumin and various functional markers in addition to several markers of health status. These data suggest an association between ILA and aging. However, no association was found with other suggested markers of aging. This could be because of the complicated nature of aging and the lack of consensus on biomarkers of aging. Still, the findings presented here indicate that people with ILA have worse physical health than their peers, thus implying that ILA is a pathological condition and adding to the body of evidence suggesting that the early stages of interstitial lung disease are an ideal target for research aimed at finding ways of their treatment and prevention.
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