Risk factors for rheumatoid arthritis-associated interstitial lung disease: a retrospective study.

Background: The objective of this study was to assess clinical and imaging features of rheumatoid arthritis (RA) associated with interstitial lung disease (ILD), (RA-ILD) group, in comparison to RA without ILD (RA-C) and to identify the associated factors to ILD.

Methods: This was a retrospective comparative study (from June 2015 to March 2022) including RA patients aged ≥18 years. The RA-C control group was matched according to age (±2 years), gender, and RA duration (±2 years). General data, RA characteristics, ILD features, and treatment modalities were recorded. Statistical analysis was performed to determine the predictive factors of ILD.

Results: A total of 104 patients were included (52 RA-ILD and 52 RA-C); sex ratio was 0.36. Mean age was 66.3±11 years (RA-ILD) 65.6±10.8 years (RA-C) (p=0.72). In comparison to RA-C, RA-ILD patients were significantly higher smokers (p=0.01) and physically inactive (p=0.01). Regarding RA features, RA-ILD patients have significantly increased positive anti-citrullinated peptide antibody (ACPA) (p=0.01), ACPA rate (p<0.001), erosive disease (p<0.001), and disease activity score (p<0.001). Mean time to ILD diagnosis was 5.85±7.16 years. Chest high-resolution computed tomography (HRCT) patterns of disease were identified: nonspecific interstitial pneumonia (NSIP) (28.8%), usual interstitial pneumonia (UIP) (17.3%), organizing pneumonia (OP) (25%), acute interstitial pneumonia (13.5%), and respiratory bronchiolitis (3.8%). Multivariate analysis identified smoking, high baseline DAS28 (disease activity score 28) and ACPA positivity as predictive factors of ILD.

Conclusion: Our results confirmed the reported associated factors of ILD in RA (smoking, higher disease activity, ACPA positivity). Thus, we need to target the modifiable factors by supporting and educating RA patients to quit smoking and intensify disease modifying anti-rheumatoid drugs (DMARD) to reach remission.