Suspected Interstitial Lung Disease in COPDGene Study.

RATIONALE While interstitial lung abnormalities (ILA), specific patterns of incidentally-detected abnormal density on computed tomography (CT), have been associated with abnormal lung function and increased mortality, it is unclear if a subset with incidental interstitial lung disease (ILD) accounts for these adverse consequences. OBJECTIVES To define the prevalence and risk factors of suspected ILD and assess outcomes. METHODS Suspected ILD was evaluated in the COPDGene cohort, defined as ILA and at least one additional criterion: definite fibrosis on CT, FVC less than 80% predicted, or DLCO less than 70% predicted. Multivariable linear, longitudinal, and Cox proportional hazards regression models were used to assess associations with St. George's Respiratory Questionnaire (SGRQ), Six-Minute Walk Test (6MWT), supplemental oxygen use, respiratory exacerbations, and mortality. MEASUREMENTS AND MAIN RESULTS Of 4361 participants with available data, 239 (5%) had evidence for suspected ILD while 204 (5%) had ILA without suspected ILD. In multivariable analyses, suspected ILD was associated with increased SGRQ score (mean difference [MD] 3.8points; 95% confidence interval [CI] 0.6-7.1; P=0.02), reduced 6MWT (MD -35m; 95%CI -56m,-13m; P=0.002), greater supplemental oxygen use (odds ratio [OR] 2.3; 95%CI 1.1-5.1; P=0.03) and severe respiratory exacerbations (OR 2.9; 95%CI 1.1-7.5; P=0.03), and higher mortality (hazard ratio 2.4; 95%CI 1.2-4.6; P=0.01) compared to ILA without suspected ILD. Risk factors associated with suspected ILD included self-identified black race (OR 2.0; 95%CI 1.1-3.3; P=0.01) and pack-years smoking history (OR 1.2; 95%CI 1.1-1.3; P=0.0005). CONCLUSION Suspected ILD is present in half of those with ILA in COPDGene and is associated with exercise decrements and increased symptoms, supplemental oxygen use, severe respiratory exacerbations, and mortality.