A preliminary study of lung abnormalities on HRCT in patients of rheumatoid arthritis-associated interstitial lung disease with progressive fibrosis

Objective: This retrospective study evaluates lung abnormalities on high-resolution CT (HRCT) and clarifies which abnormality can predict the progressive fibrosis of rheumatoid arthritis (RA)-associated interstitial lung disease (ILD).

Objects and methods: We identified 1096 RA patients, and enrolled 213 patients with a diagnosis of RA-ILD who underwent serial chest HRCT. Clinical data of the patients were obtained. The presence, extent, and distribution of lung abnormalities were assessed on CT scans. Logistic regression analysis was used to determine positive indicators with predictive value for progressive fibrosis, and 2 × 2 contingency tables were constructed to assess their diagnostic efficiency.

Result: Of 213 RA-ILD patients, 106 (49.8%) were diagnosed as progressive fibrosis. The rates of advanced age, male, smoking history, shortness of breath, and anti-CCP antibody high titer positive were higher, and RA duration was shorter in progressive fibrosis patients. Reticular pattern (RP), peribronchovascular interstitium (PBVI) thickening, interlobular septal thickening, and traction bronchiolectasis were more common in the progressive fibrosis group (84.9% vs 42.1%, P < 0.001; 79.3% vs 45.8%, P < 0.001; 74.5% vs 43.9%, P < 0.001; 67.0% vs 40.2%, P < 0.001; respectively). Lung abnormalities demonstrated subpleural predominance, and the subpleural RP and/or interlobular septal thickening had a wide distribution in the progressive fibrosis group (71.7% vs 14.0%, P < 0.001). The overall extent of lung abnormalities was more extensive in the progressive fibrosis group (18.4% vs 14.2%, P < 0.05). Logistic regression analysis showed that a wide distribution of subpleural RP and/or interlobular septal thickening (OR, 18.15) and PBVI thickening (OR, 4.98) were independent risk factors predictive of progressive fibrosis. For the combination of these two CT abnormalities, sensitivity was 63.2%, specificity was 92.5%, positive likelihood ratio was 8.5, and negative likelihood ratio was 0.4 in predicting progressive fibrosis.

Conclusions: A wide distribution of subpleural RP and/or interlobular septal thickening and PBVI thickening on HRCT appear predictive of progressive fibrosis in RA-ILD. The combined evaluation of these two CT abnormalities has a good judgment value. Key Points • We designed this study to investigate the risk factors for progressive fibrosis in patients with RA-ILD. Factors including clinical, physiological, radiological and therapeutic variables were all included in the data analysis. • Our results showed HRCT abnormalities, rather than other parameters, appeared predictive of progressive fibrosis in RA-ILD. • The methods and results of image evaluation in this article would provide reference to rheumatologists in identifying early stage of progressive fibrosis which helps to improve poor prognosis of RA-ILD.