Background: 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.
Material and methods: 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.
Results: 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.
Conclusions: 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.