Background: Interstitial lung disease (ILD) in Rheumatoid Arthritis (RA) can be subclinical or underestimated. Data from the literature report male sex, seropositivity and old age as known risk factors for ILD in RA. However, the correct timing for referral to pneumologists and eligibility for CT chest scan is undefined.

Objectives: To identify potential red flags of ILD diagnosis for referral to a multidisciplinary team analyzing clinical and radiological findings associated with the establishment of ILD.

Methods: Retrospective study on CT chest scan from RA patients evaluated and categorized into usual interstitial pneumonia (UIP), nonspecific interstitial pneumonia (NSIP) and unclassifiable RA-ILD (Un-ILD), by two radiologists. RA-ILD was diagnosed by two pneumologists considering radiological and clinical factors.

Results: 80 CT chest scans from RA patients (F 59, age 66,6 ± 11,4, disease duration 7,8 ± 4,4) were evaluated. 36,5% of patients had performed CT-chest scan for suspect of ILD, 11,2% for probable pulmonary infection, 8,7% for oncological screening or follow up, 13,7% for COPD disease, 8,7% for screening or active TBC, 3,7% for screening or previous pleuritis and 17,5% for other reasons. A RA-ILD pattern was identified in 35% of patients, with a defined UIP pattern in 17,8%, a defined NSIP pattern in 42,8% and a 39,3% of Un-ILD, while 65% of patients had a non-ILD lung involvement by CT-scan. The mean age at ILD diagnosis was 67,2 years and the mean time between RA diagnosis and onset of ILD symptoms was 7,4 years.

In the multivariate analysis female sex (HR=0,33; p=0,006) and disease duration (HR=0,8; p=0,06) were protective factors for ILD diagnosis. Age (HR=1,1; p=0,03), use of leflunomide (HR=10,1; p=0,03) were negative prognostic factors for ILD. Pulmonary clinical symptoms as dry cough (HR=17,6; p=0,02), bibasilar inspiratory crackles (HR=11,5; p=0,01) and pleural rubs (HR=18,1; p=0,03) predicted ILD while negative predictors were the presence of linear opacities (HR=99,9; p=0,006), interstitial abnormalities (HR=12,1; p=0,07) and cystic areas (HR=33,3; p=0,06) at chest CT scan.

Conclusion: In our cohort the first ILD symptom appeared 7.4 years after RA diagnosis. Clinical variables and radiological abnormalities were identified as highly predictive of ILD diagnosis and may represent red flags for an early diagnosis and referral to pneumologists and radiologists in a multidisciplinary approach.

Disclosure of Interests: None declared