Rheumatoid arthritis-related interstitial lung disease (RA-ILD): methotrexate and the severity of lung disease are associated to prognosis.

Interstitial lung disease (ILD) is a severe rheumatoid arthritis (RA) manifestation. The worst survival has been associated with usual interstitial pneumonia (UIP) definitive pattern in high-resolution chest tomography (HRCT) scans. Moreover, the use of methotrexate in RA-ILD is controversial. Our aim was to evaluate prognostic factors including methotrexate in an RA-ILD cohort and their association with survival. RA-ILD patients referred for medical evaluation and treatment at a single center were included. At the baseline, pulmonary function tests were carried out and a HRCT was obtained. A radiologist evaluated the ILD tomographic pattern and the extent of lung disease. Patients were considered as receiving methotrexate therapy if this drug was specifically prescribed for the treatment of RA-ILD at the beginning of follow up. Seventy-eight patients were included. UIP definite pattern in HRCT was not associated to worse survival. Variables associated with mortality reflected the severity of lung disease. Treatment with methotrexate was associated with survival (HR 0.13, 95% CI 0.02-0.64); older patients had worse prognosis (HR 1.04, 95% CI 1.003-1.09). After adjusting for confounding variables, methotrexate was strongly associated with survival. Methotrexate treatment during follow up was associated with survival. The severity of lung disease and not the tomographic pattern is associated with mortality; older patients had worse prognosis.