Interstitial lung abnormalities and physical function

A Comprehensive Review of Interstitial Lung Abnormalities

Interstitial lung abnormalities (ILAs) represent radiological entities that comprise changes compatible with an interstitial process, occurring in individuals not suspected to have interstitial lung disease (ILD). The prevalence of ILAs ranges from 2.5% to 16.7% in lung cancer screening and population-based cohorts. ILAs have consistently been associated with mortality. Risk factors include older age, smoking, and genetic polymorphisms such as MUC5B. Progression of ILAs occurs in 20%-76% of cases over 2-6 years of follow-up. The clinical approach to ILAs involves risk stratification based on radiological features, extent of involvement, and associated clinical and physiological findings. ILAs pose a significant challenge in distinguishing inconsequential radiological findings from early ILD. This review summarises the current understanding of ILAs, including prevalence, risk factors, progression, associated biomarkers, and clinical management strategies.

Interstitial Lung Abnormalities: Current Understanding

Interstitial lung abnormalities (ILAs) are incidental findings on computed tomography scans, characterized by nondependent abnormalities affecting more than 5% of any lung zone. They are associated with factors such as age, smoking, genetic variants, worsened clinical outcomes, and increased mortality. Risk stratification based on clinical and radiological features of ILAs is crucial in clinical practice, particularly for identifying cases at high risk of progression to pulmonary fibrosis. Traction bronchiectasis/bronchiolectasis index has emerged as a promising imaging biomarker for prognostic risk stratification in ILAs. These findings suggest a spectrum of fibrosing interstitial lung diseases, encompassing from ILAs to pulmonary fibrosis.

Clinical outcomes of interstitial lung abnormalities: a systematic review and meta-analysis

Interstitial lung abnormalities (ILA), incidental findings on computed tomography scans, have raised concerns due to their association with worse clinical outcomes. Our meta-analysis, which included studies up to April 2023 from PubMed/MEDLINE, Embase, and Cochrane Library, aimed to clarify the impact of ILA on mortality, lung cancer development, and complications from lung cancer treatments. Risk ratios (RR) with 95% confidence intervals (CI) were calculated for outcomes. Analyzing 10 studies on ILA prognosis and 9 on cancer treatment complications, we found that ILA significantly increases the risk of overall mortality (RR 2.62, 95% CI 1.94-3.54; I2 = 90%) and lung cancer development (RR 3.85, 95% CI 2.64-5.62; I2 = 22%). Additionally, cancer patients with ILA had higher risks of grade 2 radiation pneumonitis (RR 2.28, 95% CI 1.71-3.03; I2 = 0%) and immune checkpoint inhibitor-related interstitial lung disease (RR 3.05, 95% CI 1.37-6.77; I2 = 83%) compared with those without ILA. In conclusion, ILA significantly associates with increased mortality, lung cancer risk, and cancer treatment-related complications, highlighting the necessity for vigilant patient management and monitoring.

The HLA-DRB1*07 Allele Is Associated with Interstitial Lung Abnormalities (ILA) and Subpleural Location in a Mexican Mestizo Population

Interstitial lung abnormalities (ILA) are defined as the presence of different patterns of increased lung density, including ground glass attenuation and reticular opacities on chest high-resolution computed tomography (HRCT). In this study, we included 90 subjects with ILA and 189 healthy controls (HC) from our Aging Lung Program. We found that subjects with ILA are older, have a significant smoking history, and have worse pulmonary function than HC (p < 0.05). When we evaluated the allele frequencies of the human leukocyte antigen (HLA) system, we found that HLA-DRB1*07 was associated with a higher risk for ILA (p < 0.05, OR = 1.95, 95% CI = 1.06-3.57). When we compared subjects with subpleural ILA vs. HC, the association with HLA-DRB1*07 became stronger than the whole ILA group (p < 0.05, OR = 2.29, 95% CI = 1.24-4.25). Furthermore, subjects with subpleural ILA and central ILA display differences in allele frequencies with HLA-DRB1*14 (3.33% vs. 13.33%, p < 0.05) and *15 (3.33% vs. 20%, p < 0.05). Our findings indicate that the HLA-DRB1*07 allele contributes to the risk of ILA, especially those of subpleural locations.

Interstitial lung abnormalities are associated with decreased mean telomere length

BACKGROUND

Interstitial lung abnormalities (ILA) share many features with idiopathic pulmonary fibrosis; however, it is not known if ILA are associated with decreased mean telomere length (MTL).

METHODS

Telomere length was measured with quantitative PCR in the Genetic Epidemiology of Chronic Obstructive Pulmonary Disease (COPDGene) and Age Gene/Environment Susceptibility Reykjavik (AGES-Reykjavik) cohorts and Southern blot analysis was used in the Framingham Heart Study (FHS). Logistic and linear regression were used to assess the association between ILA and MTL; Cox proportional hazards models were used to assess the association between MTL and mortality.

RESULTS

In all three cohorts, ILA were associated with decreased MTL. In the COPDGene and AGES-Reykjavik cohorts, after adjustment there was greater than twofold increase in the odds of ILA when comparing the shortest quartile of telomere length to the longest quartile (OR 2.2, 95% CI 1.5-3.4, p=0.0001, and OR 2.6, 95% CI 1.4-4.9, p=0.003, respectively). In the FHS, those with ILA had shorter telomeres than those without ILA (-767 bp, 95% CI 76-1584 bp, p=0.03). Although decreased MTL was associated with chronic obstructive pulmonary disease (OR 1.3, 95% CI 1.1-1.6, p=0.01) in COPDGene, the effect estimate was less than that noted with ILA. There was no consistent association between MTL and risk of death when comparing the shortest quartile of telomere length in COPDGene and AGES-Reykjavik (HR 0.82, 95% CI 0.4-1.7, p=0.6, and HR 1.2, 95% CI 0.6-2.2, p=0.5, respectively).

CONCLUSION

ILA are associated with decreased MTL.

Increased monocyte level is a risk factor for radiological progression in patients with early fibrotic interstitial lung abnormality

Background

Interstitial lung abnormalities (ILA) are specific spatial patterns on computed tomography (CT) scan potentially compatible with early interstitial lung disease. A proportion will progress; management involves risk stratification and surveillance. Elevated blood monocyte levels have been shown to associate with progression of idiopathic pulmonary fibrosis. The aims of the present study were: 1) to estimate the proportion of “early fibrotic” (EF)-ILAs (reticular±ground-glass opacities, excluding traction bronchiectasis and honeycombing) on CT scans of patients attending all-indications thoracic CTs, and proportion demonstrating radiological progression; and 2) to explore association between peripheral blood leukocyte levels and ILA progression.

Methods

We analysed all thoracic CT reports in individuals aged 45–75 years performed between January 2015 and December 2020 in one large teaching hospital (Oxford, UK) to identify patient CT reports consistent with EF-ILA. CT-contemporaneous blood leukocyte counts were examined to explore contribution to progression and all-cause mortality, using multivariate Cox regression.

Results

40 711 patients underwent thoracic CT imaging during this period. 1259 (3.1%) demonstrated the EF-ILA pattern (mean±sd age 65.4±7.32 years; 735 (47.8%) male). EF-ILA was significantly associated with all-cause mortality (hazard ratio 1.87, 95% CI 1.25–2.78; p=0.002). 362 cases underwent at least one follow-on CT. Radiological progression was observed in 157 (43.4%) cases: increase in reticulation n=51, new traction bronchiectasis n=84, honeycombing n=22. Monocyte count, neutrophil count, monocyte:lymphocyte ratio, neutrophil:lymphocyte ratio and “systemic inflammatory response index” were significantly associated with radiological progression.

Conclusion

3.1% of subjects requiring thoracic CT during a 6-year period demonstrated EF-ILA. Monocyte levels and blood leukocyte-derived indexes were associated with radiological progression and could indicate which patients may require closer follow-up.

Monocyte levels are associated with radiological progression of early fibrotic ILA to established interstitial lung disease and could indicate which patients might require closer follow-uphttps://bit.ly/3LlS2ff

Interstitial lung abnormalities - current knowledge and future directions

Efforts to grasp the significance of radiologic changes similar to interstitial lung disease (ILD) in undiagnosed individuals have intensified in the recent decade. The term interstitial lung abnormalities (ILA) is an emerging definition of such changes, defined by visual examination of computed tomography scans. Substantial insights have been made in the origins and clinical consequences of these changes, as well as automated measures of early lung fibrosis, which will likely lead to increased recognition of early fibrotic lung changes among clinicians and researchers alike.

Interstitial lung abnormalities have an estimated prevalence of 7–10% in elderly populations. They correlate with many ILD risk factors, both epidemiologic and genetic. Additionally, histopathological similarities with IPF exist in those with ILA. While no established blood biomarker of ILA exists, several have been suggested. Distinct imaging patterns indicating advanced fibrosis correlate with worse clinical outcomes. ILA are also linked with adverse clinical outcomes such as increased mortality and risk of lung cancer.

Progression of ILA has been noted in a significant portion of those with ILA and is associated with many of the same features as ILD, including advanced fibrosis. Those with ILA progression are at risk of accelerated FVC decline and increased mortality. Radiologic changes resembling ILD have also been attained by automated measures. Such measures associate with some, but not all the same factors as ILA.

ILA and similar radiologic changes are in many ways analogous to ILD and likely represent a precursor of ILD in some cases. While warranting an evaluation for ILD, they are associated with poor clinical outcomes beyond possible ILD development and thus are by themselves a significant finding. Among the present objectives of this field are the stratification of patients with regards to progression and the discovery of biomarkers with predictive value for clinical outcomes.

Interstitial lung abnormalities: What do we know and how do we manage?

INTRODUCTION

Interstitial lung abnormalities (ILAs), which refer to mild or subtle nongravity-dependent interstitial changes, may be neglected by some clinicians due to many reasons, such as lack of diagnostic criteria for ILAs and absence of available treatments and surveillance strategies. However, without intervention, some ILAs may progress to interstitial lung disease (ILD). This review summarizes our current knowledge of this condition and ways of diagnosing it together with current management. We hope that this will lead to better recognition of ILAs.

AREAS COVERED

We reviewed the literature on PubMed between 2008 and 2020 focusing on prevalence, etiology, symptoms, diagnostic biomarkers, clinical associations, and management of ILAs.

EXPERT OPINION

Timely diagnosis with close monitoring of ILAs and appropriate intervention should be recognized as the management approach to ILAs. Research into ILAs should continue to improve its management.

The associations of interstitial lung abnormalities with cancer diagnoses and mortality

An increased incidence of lung cancer is well known among patients with idiopathic pulmonary fibrosis. It is not known whether interstitial lung abnormalities, i.e. early fibrotic changes of the lung, are a risk factor for lung cancer in the general population.The study's objective was to assess whether interstitial lung abnormalities were associated with diagnoses of, and mortality from, lung cancer and other cancers. Data from the AGES-Reykjavik study, a cohort of 5764 older Icelandic adults, were used. Outcome data were ascertained from electronic medical records. Gray's tests, Cox proportional hazards models and proportional subdistribution hazards models were used to analyse associations of interstitial lung abnormalities with lung cancer diagnoses and lung cancer mortality as well as diagnoses and mortality from all cancers.There was a greater cumulative incidence of lung cancer diagnoses (p<0.001) and lung cancer mortality (p<0.001) in participants with interstitial lung abnormalities than in others. Interstitial lung abnormalities were associated with an increased hazard of lung cancer diagnosis (hazard ratio 2.77) and lung cancer mortality (hazard ratio 2.89) in adjusted Cox models. Associations of interstitial lung abnormalities with all cancers were found in models including lung cancers but not in models excluding lung cancers.People with interstitial lung abnormalities are at increased risk of lung cancer and lung cancer mortality, but not of other cancers. This implies that an association between fibrotic and neoplastic diseases of the lung exists from the early stages of lung fibrosis and suggests that interstitial lung abnormalities could be considered as a risk factor in lung cancer screening efforts.

Interstitial lung abnormalities: erecting fences in the path towards advanced pulmonary fibrosis

Interstitial lung abnormalities, when present in members of undiagnosed family members recruited on the basis of familial interstitial pneumonia, or in undiagnosed research participants, have been associated with a syndrome that includes distinct sets of imaging abnormalities, restrictive physiological and exercise impairments, and an increased prevalence of histopathological findings, and genetic predictors, that have been noted in patients with idiopathic pulmonary fibrosis. Recent longitudinal studies have demonstrated that qualitative and quantitative assessments of interstitial abnormalities are associated with accelerated lung function decline, an increased rate of clinical diagnoses of interstitial lung disease and an increased rate of mortality. In this perspective, in addition to reviewing the prior information, four major efforts that could help the field of early pulmonary fibrosis detection move forward are discussed. These efforts include: (1) developing standards for characterising and reporting imaging findings from patients with existing CTs; (2) developing consensus statements on when undiagnosed and asymptomatic imaging abnormalities should be considered a disease; (3) identifying populations for which screening efforts might be beneficial; and (4) considering approaches to developing effective secondary prevention trials.