Retrospective study of the clinical characteristics and risk factors of rheumatoid arthritis-associated interstitial lung disease

This study aims to explore the clinical characteristics and risk factors of rheumatoid arthritis (RA)-associated interstitial lung disease (ILD). This is a retrospective study of 550 patients with RA. All patients underwent chest high-resolution computed tomography (HRCT) scanning. (1) Two hundred thirty-seven out of five hundred fifty (43.1%) patients with RA were diagnose with ILD. 13.5% ILD occurred before RA onset, 69.6% ILD occurred within 10 years of RA onset, and 16.9% ILD occurred more than 10 years after RA onset. (2) The most common chest CT characteristics of RA-ILD included reticular patterns (57.8%), pleural thickening (57%), ground-glass attenuation (53.2%), followed by interlobular septum thickening, nodules, emphysematous bullae, honeycombing, and bronchiectasis. The proportion of the UIP pattern and NSIP on HRCT was 18.6% and 57.8%. (3) RA-ILD was often associated with other lung lesions, including pleural disease, bronchiectasis, and pulmonary hypertension. (4) the comparisons between RA with ILD and RA without ILD showed that male, smoking, age, disease duration, number of swelling joints, globulin levels, erythrocyte sedimentation rate, C-reactive protein levels, lactate dehydrogenase, the positive rate of rheumatoid factor (RF) and the absolute value of RF, forced vital capacity, forced expiratory volume in 1 s, and carbon monoxide diffusion rate, were statistically different (P < 0.05). Logistic regression analysis showed that age, smoking, elevated lactate dehydrogenase, and RF positive were closely correlated to RA-ILD. RA-ILD occurs more often within 10 years of RA onset and coexists with other lung lesions. The elevated lactate dehydrogenase, RF positive, smoking, and advanced age are closely correlated with RA-ILD.