Are interstitial lung abnormalities associated with COPD? A nested case–control study

Abstract

PurposeIn this study, we tested the association between COPD and interstitial lung abnormality (ILA), notably in relation to the presence of computed tomography (CT) signs of lung fibrosis.Patients and methodsCOPD cases were selected from participants undergoing lung cancer screening (Multicentric Italian Lung Detection trial) for airflow obstruction (n=311/2,303, 13.5%) and 146 consecutive patients with clinical COPD. In all, 457 COPD cases were selected and classified according to the stages of Global Initiative for Chronic Obstructive Lung Disease. A nested matching (case:control = 1:2) according to age, sex, and smoking history was operated between each COPD case and two control subjects from Multicentric Italian Lung Detection trial without airflow obstruction. Low-dose CT scans of COPD cases and controls were reviewed for the presence of ILA, which were classified into definite or indeterminate according to the presence of signs of lung fibrosis.ResultsThe frequency of definite ILA was similar between COPD cases and controls (P=0.2), independent of the presence of signs of lung fibrosis (P=0.07). Combined definite and indeterminate ILA was homogeneously distributed across Global Initiative for Chronic Obstructive Lung Disease stages (P=0.6). Definite ILA was directly associated with current smoker status (odds ratio [OR] 4.05, 95% confidence interval [CI]: 2.2–7.4) and increasing pack-years (OR 1.01, 95% CI: 1–1.02). Subjects with any fibrotic ILA were more likely to be older (OR 1.17, 95% CI: 1.10–1.25) and male (OR 8.58, 95% CI: 1.58–68.9).ConclusionThere was no association between COPD and definite ILA. However, low-dose CT signs of lung fibrosis were also observed in COPD, and their clinical relevance is yet to be determined.

Increased respiratory morbidity in individuals with interstitial lung abnormalities

“…The association between ILA and clinically diagnosed COPD during long-term follow-up is intriguing, as it contradicts some earlier cross-sectional and case control findings but is supported by others [6,27,28]. Our results could be due to the study population derived from a lung cancer screening trial, the longitudinal follow-up or a different definition of clinical disease.…”

Incidental discovery of interstitial lung disease: diagnostic approach, surveillance and perspectives

“…However, a study designed specifically to address the association between COPD and ILA did not show any linkage. In COPD cases from Multicentric Italian Lung Detection trial (n=457) analysed with a nested matching case: control of 1:2 according to age, gender and smoking history, a similar frequency of definite ILA between cases and controls was shown ( p=0.20), independent of the presence of signs of lung fibrosis ( p=0.07) [59]. By contrast, LEE et al [60] evaluated 363 patients with COPD, 44 and 103 having respectively equivocal and definite ILA, and showed an association between ILA and the annual incidence of moderate to severe acute exacerbations (adjusted OR 2.03; p=0.45).…”

“…By contrast, LEE et al [60] evaluated 363 patients with COPD, 44 and 103 having respectively equivocal and definite ILA, and showed an association between ILA and the annual incidence of moderate to severe acute exacerbations (adjusted OR 2.03; p=0.45). In summary, low-dose CT signs of lung fibrosis can also be observed in COPD, but their clinical relevance remains to be determined and recent data on associations between COPD exacerbations and the presence of ILA are conflicting [59][60][61].…”

Increased Respiratory Morbidity in Individuals with Interstitial Lung Abnormalities

“…(25,26) The association between ILA and clinically diagnosed COPD during long-term follow-up is intriguing, as it contradicts some earlier cross-sectional and case control findings but is supported by others. (6,27,28) Our results could be due to the study population derived from a lung cancer screening trial, the longitudinal follow-up or a different definition of clinical disease. First, we included long-term smokers from a lung cancer screening trial and followed them for up to 12 years, which may affect the incidence of COPD as both age and tobacco exposure are known risk factors of COPD.…”