Incidence of interstitial lung abnormalities: the MESA Lung Study

The incidence of newly developed interstitial lung abnormalities (ILA) and fibrotic ILA has not been previously reported.

Trained thoracic radiologists evaluated 13 944 cardiac computed tomography scans for the presence of ILA in 6197 Multi-Ethnic Study of Atherosclerosis (MESA) longitudinal cohort study participants >45 years of age from 2000 to 2012. Five percent of the scans were re-read by the same or a different observer in a blinded fashion. After exclusion of participants with ILA at baseline, incidence rates and incidence rate ratios for ILA and fibrotic ILA were calculated.

The intra-reader agreement of ILA was 92.0% (Gwet's AC1 0.912, intraclass correlation coefficient (ICC) 0.982) and the inter-reader agreement of ILA was 83.5% (Gwet's AC1 0.814, ICC 0.969). Incidence of ILA and fibrotic ILA was estimated to be 13.1 and 3.5 cases per 1000 person-years, respectively. In multivariable analyses, age (hazard ratio (HR) 1.06 (95% CI 1.05-1.08); p<0.001 and HR 1.08 (95% CI 1.06-1.11); p<0.001), high attenuation area at baseline (HR 1.05 (95% CI 1.03-1.07); p<0.001 and HR 1.06 (95% CI 1.02-1.10); p=0.002) and the MUC5B promoter single nucleotide polymorphism (HR 1.73 (95% CI 1.17-2.56); p=0.01 and HR 4.96 (95% CI 2.68-9.15); p<0.001) were associated with incident ILA and fibrotic ILA, respectively. Ever-smoking (HR 2.31 (95% CI 1.34-3.96); p=0.002) and an idiopathic pulmonary fibrosis polygenic risk score (HR 2.09 (95% CI 1.61-2.71); p<0.001) were associated only with incident fibrotic ILA.

Incident ILA and fibrotic ILA were estimated by review of cardiac imaging studies. These findings may lead to wider application of a screening tool for atherosclerosis to identify pre-clinical lung disease.