Interstitial lung disease (ILD) in rheumatoid arthritis (RA) is associated with a poor prognosis. The purpose of this study was to assess the characteristics of ILD that are associated with RA.
This was a retrospective study of 544 Chinese patients with RA (427 women and 117 men). RA-ILD was diagnosed by high-resolution computed tomography (HRCT). Patients with RA-ILD or with RA alone were compared in terms of age, sex distribution, duration of disease, clinical and laboratory parameters, history of smoking, and medication.
Based on HRCT imaging, 83 (15.26%) patients with RA were diagnosed with ILD. ILD was more frequent in older patients (59.60±9.66 vs. 50.54±13.76 years, P<0.001), in those with a longer duration of disease (7.46±7.40 vs. 5.27±6.32 years, P=0.013) and in male patients (34.9% vs. 19.1%, P=0.001). RA-ILD was found to be associated with hepatitis B surface antigen (HBsAg) positivity (odds ratio [OR]=2.56, 95% confidence interval [95% CI] 1.02-6.43) and smoking (OR=3.38, 95% CI 1.65-6.95). Higher levels of C-reactive protein (OR=3.59, 95% CI 1.58-8.15), anti-cyclic citrullinated peptide (CCP) (OR=2.24, 95% CI 2.09-4.13), and rheumatoid factor (OR=3.72, 95% CI 1.56-8.86) were detected in association with RA-ILD. RA-ILD was more frequently observed in patients treated with steroids (OR=1.91, 95% CI 1.18-3.09) or Tripterygium wilfordii (OR=2.56, 95% CI 1.21-5.40). Age (OR=2.20, 95% CI 1.04-4.65), age at RA onset (OR=2.55, 95% CI 1.11-5.90), anti-CCP (OR=2.47, 95% CI 1.19-5.17), and steroid use (OR=1.83, 95% CI 1.04-3.20) were independently associated with RA-ILD in multivariate analysis.
RA-ILD was associated with age, age at RA onset, anti-CCP, and steroid use. Anti-CCP antibodies might be important biomarkers of RA-ILD.