Background: Rheumatoid arthritis (RA) associated lung disease is a relatively frequent extra articular disease manifestation, with a prevalence between 5% and 30%. The rather wide range of estimated prevalence is a result of differences in study designs and studied populations, as well as lacking diagnostic and classification criteria for lung disease in patients with RA.

Objectives: To evaluate the prevalence of RA associated lung disease in patients with biological therapy (BT), as well as its severity, treatment changes and possible associated factors.

Methods: Review of clinical records of 257 patients with RA treated with BT (TNFi, non-TNFi) between January 2015 to December 2020 in a single center. Patients with preexisting lung disease for other causes (asthma, smoking) have been excluded. RA diagnosis was performed according to ACR 2010 classification criteria. Epidemiological variables, clinical characteristics, type of pulmonary involvement, evolution, type of BT, changes in treatment and concomitant treatment were collected. For the analysis frequencies and percentages are used in qualitative variables, and mean ± SD in the quantitative ones. Statistical analysis was performed with IBM SPSS v 23.

Results: We registered 21 patients (85.7% women) mean aged 70.3±11.9 years. 52.4% were never smokers. RF was positive in 100% and 20 patients were anti-CCP positive. Erosive disease was present in 13 (61.9%) patients.

At the time of lung disease diagnosis, 15 patients (66.7%) were receiving TNFi (Etanercept 7, Adalimumab 6, Infliximab 1, Golimumab 1), 2 were with non-TNFi (Rituximab) and 4 had never received BT previously. Symptoms (cough and/or dyspnea) were reported in 10 (47.6%) patients. The median time of treatment with BT until lung disease diagnosis was 33 [15.5-95.5] months. Conventional synthetic DMARDs (csDMARDs) were used in 85.7% of cases (methotrexate 72.2%, leflunomide 22.2%, other 5.6%). The inflammatory activity was mild (DAS28: 3.22±1.6). The median time until lung disease diagnosis was 104 [56.2-156] months.

After the lung disease diagnosis, BT was only modified in 1 patient. In the 4 patients who had not previously received BT, non-TNFi was started (Rituximab 2, Abatacept 1, Tocilizumab 1). csDMARD was discontinued in 1 patient.

Interstitial lung disease (ILD) was the most frequent pulmonary involvement (16 patients, 76.2%): 8 usual interstitial pneumonia (UIP), 6 non-specific interstitial pneumonia (NSIP), 1 organising pneumonia (OP) and 1 lymphocytic interstitial pneumonia (LIP). Other pulmonary manifestations observed in our patients were: nodular lung disease (2 patients) and small airways disease (bronchiectasis 2, obliterative bronchiolitis 1). Chest x-ray was normal in almost half of the patients (42.9%). Gold standard image diagnostic technique was high resolution CT.

In respiratory function tests (PFTs) at diagnosis, only 4 patients (19%) had a FVC<80% and 4 (19%) a DLCO<60%. In the following 2 years, in 2 patients the FVC worsened > 10% and in 5 there was a worsening of the DLCO > 15%. In 3 (14.3%) patients PFTs were never performed and in 7 (43.7%) were not repeated after the diagnosis.

We haven´t found association between different types of pulmonary involvement and the variables analysed.

Conclusion: In our series, prevalence of RA associated lung disease is similar to that described in the literature. Lung involvement is asymptomatic and chest X-ray is normal in most RA patients. High resolution CT is the gold standard for diagnosis.

ILD was the most frequent pulmonary involvement. Although in most patients the diagnosis of lung disease did not imply a BT change, it had an influence on the type of BT chosen for those who started treatment. Maintenance of csDMARD was not associated with a worsening of lung disease.

Screening and treatment protocols for lung disease in patients with RA in clinical practice are needed.

Disclosure of Interests: None declared