Background: Interstitial lung disease (ILD) is a well-known and severe systemic complication of numerous rheumatologic diseases. The management of these entities is still under study, being both mofetil mycophenolate (MMF) and rituximab (RTX) therapeutic alternatives used in routine clinical practice.

Objectives: To compare the effectiveness of mycophenolate mofetil and rituximab in routine clinical practice as a treatment for interstitial lung disease associated with systemic autoimmune rheumatic disease (SARD) or with autoimmune features.

Methods: A retrospective observational study of patients from the Rheumatology department of a tertiary hospital diagnosed with ILD, who received treatment with MMF or RTX from 2012 to 2022. Demographic, clinical, and ILD progression data (respiratory symptoms, pulmonary function tests (PFT), and radiological progression) were collected. Stability of PFT was defined as a variation <10% of FVC or <15% of DLCO. Attempts were made to define patient profiles that may benefit more from each treatment. Descriptive statistics were used to define patient clinical characteristics (average, standard deviation), and we also performed the χ2 test for statistical analysis of our dataset.

Results: A total of 54 patients were included; 39 treated with MMF (72%) and 15 with RTX (28%); 36 women (67%) and 18 men (33%); the mean age was 64,27 years (SD 12.1). Systemic sclerosis was the most frequently associated SARD with ILD in 25 cases (46%), followed by rheumatoid arthritis in 10 cases (18.5%), and Sjögren’s syndrome in 5 cases (9.25%); 7 cases were described as interstitial pneumonia with autoimmune features (IPAF) (13%).

After one year of treatment, the sample treated with MMF showed stability of respiratory symptoms in 87% of the cases. PFRs were stable in 87.5% of the sample and 91% did not present radiological progression (in those cases for which control tests were available (24 and 23, respectively)). After undergoing one year of treatment, the totality of the sample treated with RTX showed stability of the respiratory symptoms. PFRs and radiological images were stable in 73% and 86% of the patients for whom spirometry and control CT scans were available (11 and 14, respectively). None of these differences reached statistically significant values.

Among patients treated with MMF, 79.5% showed no deterioration in any of these three areas; for RTX-treated patients, this situation occurred in 73% of cases. In patients with systemic sclerosis treated with MMF, deterioration in any of these areas was observed in 10.5%; for those treated with RTX, deterioration in any of these aspects was observed in 33.3%; however, these differences did not reach statistically significant values.

Conclusion: Both MMF and RTX manage to stabilize respiratory symptoms, PFT and radiological progression of ILD associated with SARD/IPAF in a significant percentage of the sample; 79.5% and 73% of cases, respectively. There is a greater tendency toward stability in cases treated with MMF, although statistically significant differences were not identified. No characteristics have been identified that condition a faster progression of ILD with statistical significance.

REFERENCES: NIL.

Acknowledgements: NIL.

Disclosure of Interests: None declared.