Are interstitial lung abnormalities associated with COPD? A nested case-control study.
OBJECTIVE
In 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.


METHODS
COPD 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.


RESULTS
The 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).


CONCLUSIONS
There 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.
Section of Radiology, Department of Surgical Sciences, University of Parma, Parma, Italy.
Francesca
F
Bozzetti
Section of Radiology, Department of Surgical Sciences, University of Parma, Parma, Italy.
Ilaria
I
Paladini
Department of Radiology, Academic Hospital of Parma, Parma, Italy.
Enrico
E
Rabaiotti
Section of Radiology, Department of Surgical Sciences, University of Parma, Parma, Italy.
Alessandro
A
Franceschini
Respiratory Disease and Lung Function Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
Veronica
V
Alfieri
Respiratory Disease and Lung Function Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
Alfredo
A
Chetta
Respiratory Disease and Lung Function Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
Ernesto
E
Crisafulli
Department of Radiology, Academic Hospital of Parma, Parma, Italy.
Mario
M
Silva
Division of Thoracic Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
Ugo
U
Pastorino
Section of Radiology, Department of Surgical Sciences, University of Parma, Parma, Italy.
Nicola
N
Sverzellati
D000367:Age Factors; D000368:Aged; D016009:Chi-Square Distribution; D016208:Databases, Factual; D005260:Female; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000000981:diagnostic imaging* / Q000453:epidemiology; D007558:Italy / Q000453:epidemiology; D016015:Logistic Models; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology; D014057:Tomography, X-Ray Computed
airspace enlargement with fibrosis; chronic obstructive lung disease; interstitial lung abnormality; usual interstitial pneumonia