Rheumatoid arthritis (RA) is one of the most common autoimmune diseases, characterized by chronic inflammatory bone and cartilage destruction. Although treatment including anti-tumor necrosis factor (TNF) and interleukin-6 (IL-6) receptor antibodies has been successful, only 20% to 30% of patients have achieved complete remission. Interstitial lung disease (ILD) is a common complication of rheumatoid arthritis (RA). Approximately 5-10% of RA patients have clinically significant rheumatoid arthritis associated interstitial lung disease (RA-ILD), with a mortality rate of 2-10 times that of RA-non ILD patients. The median survival after diagnosis is between 3-8 years. Although there are multiple biomarkers for RA-ILD, such as anti citrullinated protein antibody (ACPA), MUC5B mutant gene, KL-6, etc., none of these biomarkers can reliably predict the disease and prognostic risk of RA-ILD. Therefore, improving the prediction of RA complicated with ILD and exploring risk factors for the progression and prognosis of RA-ILD can contribute to early diagnosis and treatment, and is of great significance in preventing RA lung injury and death.

This study aims to screen differential serum biomarkers between RA patients and RA-ILD patients through prospective cohort studies, to explore whether these differential serum biomarkers are a risk factor for RA patients complicated with ILD, and whether they affect the clinical prognosis of RA-ILD patients.

Inclusion Criteria:

1. Diagnosis of rheumatoid arthritis patients based on the 2010 ACR/EULAR RA classification criteria; 2. age ≥18 years; 3. Interstitial lung disease was diagnosed by lung high resolution computed tomography (HRCT)

Exclusion Criteria:

1. age \

rheumatoid arthritis patients